All 400 quiz questions in 10 units, with the correct answer and an explanation for each. Read a unit, then test yourself in the Senior 4 quiz.
1.According to the first law of reflection, the angle of incidence is equal to the:
Answer: C
The law of reflection states that the angle of incidence equals the angle of reflection, both measured from the normal at the point of incidence.
2.A concave mirror has a focal length of 15 cm. An object is placed 20 cm in front of it. Using 1/f = 1/u + 1/v, calculate the image distance.
Answer: C
1/v = 1/f − 1/u = 1/15 − 1/20 = 1/60, so v = 60 cm. The image is real and formed 60 cm from the mirror.
3.For the mirror in the previous scenario (u = 20 cm, v = 60 cm), what is the linear magnification produced?
Answer: C
Magnification m = v/u = 60/20 = 3. The image is three times the size of the object (real and inverted).
4.A convex mirror of focal length 20 cm is placed 30 cm from an object. Taking the convex mirror's focal length as negative in the real-is-positive convention, find the image distance.
Answer: D
1/v = 1/f − 1/u = −1/20 − 1/30 = −5/60 = −1/12, so v = −12 cm. The negative sign shows the image is virtual, formed behind the mirror.
5.In the New Cartesian sign convention, a negative magnification for a mirror indicates that the image is:
Answer: A
With m = −v/u, a negative value of m corresponds to a real, inverted image; a positive m corresponds to a virtual, erect image.
6.When an object is placed between the pole and the principal focus of a concave mirror, the image formed is:
Answer: D
This is the principle used in a shaving/make-up mirror: the image is virtual, erect, and magnified when the object lies between F and the pole.
7.A spherical mirror has a radius of curvature of 40 cm. What is its focal length?
Answer: D
f = R/2 = 40/2 = 20 cm, since the principal focus lies midway between the pole and the centre of curvature.
8.The focal length of a spherical mirror is the distance between the pole of the mirror and its:
Answer: D
The focal length f is measured from the pole to the principal focus, the point where paraxial rays parallel to the principal axis converge (or appear to diverge from).
9.In the New Cartesian sign convention, distances measured against the direction of the incident light are taken as negative.
Answer: True
By convention, distances in the direction of incident light (left to right) are positive, and those measured against it are negative.
10.For a concave mirror, when the object is placed at the centre of curvature, the image formed is real, inverted, and ______ in size compared to the object.
Answer: the same (equal)
At C, u = v = R, giving magnification m = v/u = 1, so the image is the same size as the object.
11.The second law of refraction (Snell's law) states that the ratio sin i / sin r is:
Answer: A
Snell's law: n = sin i / sin r, where n is a constant (the refractive index) for a given pair of media and a given wavelength of light.
12.A ray of light strikes a glass block (n = 1.5) at an angle of incidence of 60°. What is the angle of refraction?
Answer: A
sin r = sin 60°/1.5 = 0.866/1.5 = 0.577, so r = sin⁻¹(0.577) ≈ 35.3°.
13.When light travels from air into a glass block, it bends towards the normal because, in glass, light:
Answer: D
Glass is optically denser than air, so light slows down on entering it, causing the ray to bend towards the normal.
14.When light emerges from a parallel-sided (rectangular) glass block, the emergent ray is ______ to the incident ray, though laterally displaced.
Answer: parallel
The two refractions at the parallel surfaces cancel each other's angular deviation, leaving the emergent ray parallel to the incident ray, only shifted sideways.
15.When light passes through a rectangular glass block, the emergent ray is parallel to the incident ray but laterally displaced.
Answer: True
This is a standard result of refraction through a slab with parallel faces: the net angular deviation is zero, but a lateral (sideways) shift occurs.
16.The refractive index of glass is 1.5 and the speed of light in vacuum is 3 × 10⁸ m/s. What is the speed of light in the glass?
Answer: D
n = c/v, so v = c/n = (3 × 10⁸)/1.5 = 2.0 × 10⁸ m/s.
17.The bending of light as it passes obliquely from one transparent medium into another of different optical density is called ______.
Answer: refraction
Refraction is the change in direction of a light ray as it crosses a boundary between media of different refractive indices.
18.Which of the following does NOT affect the refractive index of a given pair of media?
Answer: B
By Snell's law, n = sin i/sin r is constant for a given pair of media and wavelength regardless of the angle of incidence chosen; changing i simply changes r proportionally, keeping n fixed.
19.A swimming pool has a real depth of 3.0 m. If the refractive index of water is 1.33, what is its apparent depth when viewed from directly above?
Answer: C
Apparent depth = real depth/n = 3.0/1.33 ≈ 2.3 m.
20.A coin lies at the bottom of a glass slab of real thickness 6 cm (n = 1.5). By how much does the coin appear to be raised when viewed from directly above?
Answer: C
Apparent depth = 6/1.5 = 4 cm, so the apparent shift = 6 − 4 = 2 cm.
21.A swimming pool always looks shallower than it really is when viewed from directly above because:
Answer: A
Rays from the bottom refract away from the normal as they leave water into air, so they appear to diverge from a point closer to the surface than the true bottom, making the apparent depth less than the real depth.
22.Apparent depth is always greater than real depth when viewing an object in water from air.
Answer: False
The opposite is true: because water is optically denser than air, apparent depth is always less than real depth (apparent depth = real depth/n, and n > 1).
23.The ratio of real depth to apparent depth of an object viewed normally through a transparent medium is equal to the ______ of that medium.
Answer: refractive index
n = real depth/apparent depth for near-normal viewing.
24.A fish appears to be at a depth of 1.2 m when viewed from directly above a pond (n(water) = 4/3). What is the fish's actual (real) depth?
Answer: A
Real depth = n × apparent depth = (4/3) × 1.2 = 1.6 m.
25.The refractive index of a certain glass is 1.5. What is its critical angle for light travelling from glass to air?
Answer: B
sin C = 1/n = 1/1.5 = 0.667, so C = sin⁻¹(0.667) ≈ 41.8°.
26.Total internal reflection occurs only when:
Answer: B
Both conditions must be satisfied: the light must be travelling towards a less optically dense medium, and the angle of incidence in the denser medium must be greater than the critical angle.
27.Total internal reflection is the principle mainly responsible for the operation of:
Answer: D
In optical fibres, light undergoes repeated total internal reflection at the core–cladding boundary, allowing it to travel long distances with minimal loss.
28.Total internal reflection can occur when light travels from a less dense medium to a denser medium.
Answer: False
Total internal reflection can only occur when light travels from a denser medium towards a less dense medium, not the reverse.
29.The angle of incidence in the denser medium for which the angle of refraction is exactly 90° is called the ______.
Answer: critical angle
This is the definition of the critical angle, C, beyond which total internal reflection occurs.
30.As the refractive index of a medium increases, its critical angle (for light leaving that medium into air):
Answer: B
Since sin C = 1/n, C decreases as n increases (they are inversely related).
31.Diamond has a refractive index of about 2.42. What is its approximate critical angle?
Answer: A
sin C = 1/2.42 = 0.413, so C = sin⁻¹(0.413) ≈ 24.4°. This very small critical angle causes extensive internal reflection, giving diamond its sparkle.
32.In an optical fibre, the refractive index of the core must be greater than that of the cladding so that:
Answer: C
Total internal reflection requires light to move from a denser (core) to a less dense (cladding) medium and strike the boundary beyond the critical angle, keeping the light confined within the core.
33.A converging lens has a focal length of 10 cm. An object is placed 30 cm from the lens. Using 1/f = 1/v − 1/u (New Cartesian sign convention), find the image distance.
Answer: B
Using the Cartesian form 1/v − 1/u = 1/f with the real object at u = −30 cm: 1/v = 1/f + 1/u = 1/10 − 1/30 = 2/30 = 1/15, so v = 15 cm (a real image on the far side of the lens).
34.For the converging lens above (u = 30 cm, f = 10 cm, v = 15 cm), what type of image is formed?
Answer: C
Since the object lies beyond 2f (30 cm > 20 cm), the image forms between f and 2f (v = 15 cm), and is real, inverted, and diminished (m = v/u = 0.5).
35.A converging lens has a focal length of 10 cm. What is its power?
Answer: A
Power P = 1/f, with f in metres: P = 1/0.10 = +10 D (positive because it is a converging lens).
36.A diverging lens has a focal length of 25 cm. What is its power?
Answer: B
P = 1/f = 1/(−0.25 m) = −4 D. The power of a diverging lens is negative.
37.Two thin lenses of powers +5 D and −2 D are placed in contact. What is the focal length of the combination?
Answer: A
Combined power P = P₁ + P₂ = 5 + (−2) = +3 D, so f = 1/P = 1/3 m ≈ 33.3 cm.
38.The power of a converging (convex) lens is positive, while that of a diverging (concave) lens is negative.
Answer: True
By convention, P = 1/f, and since a converging lens has a positive focal length while a diverging lens has a negative one, their powers carry opposite signs.
39.The power of a lens is defined as the reciprocal of its focal length measured in ______, and is expressed in dioptres (D).
Answer: metres
P (in dioptres) = 1/f, where f must be expressed in metres.
40.When an object is placed between the focal point and the optical centre of a converging (convex) lens, the image formed is:
Answer: B
This is the principle of a simple magnifying glass: with the object inside the focal length, the lens produces a virtual, erect, magnified image on the same side as the object.
1.The image formed on the film/sensor of a camera photographing a distant object is:
Answer: A
A camera's converging lens forms a real, inverted image, usually diminished, on the light-sensitive film or sensor.
2.In a camera, focusing on objects at different distances is achieved by:
Answer: D
Unlike the eye, a camera lens has a fixed shape; focusing is achieved by moving the lens to adjust the lens-to-film (image) distance.
3.The diaphragm (aperture) of a camera mainly controls:
Answer: A
The aperture (adjustable opening) controls how much light passes through the lens onto the film/sensor.
4.The shutter of a camera controls:
Answer: C
The shutter opens for a set time (exposure time), determining how long light is allowed to strike the film/sensor.
5.Unlike the eye, a camera focuses images of objects at different distances by changing the lens-to-film distance rather than the focal length of the lens.
Answer: True
The camera lens has a fixed focal length; the lens itself is moved to change the image distance and keep the image sharply focused on the film.
6.The light-sensitive surface on which a real image is formed in a camera is called the ______.
Answer: film (or sensor)
In older cameras this is photographic film; in digital cameras, it is an electronic sensor (e.g., CCD/CMOS).
7.Which part of the human eye controls the amount of light entering the eye, acting like a camera's diaphragm?
Answer: A
The iris adjusts the size of the pupil to regulate the amount of light entering the eye.
8.Most of the refraction of light entering the eye occurs at the:
Answer: D
The curved cornea, together with the aqueous humour, provides most of the eye's total refractive power; the crystalline lens provides the fine adjustment for focusing.
9.During accommodation for viewing a near object, the ciliary muscles:
Answer: C
To focus on near objects, the ciliary muscles contract, allowing the elastic lens to become more curved (thicker), increasing its refractive power.
10.The retina of the eye functions mainly to:
Answer: A
The retina is the light-sensitive layer at the back of the eye where a real image forms; photoreceptor cells convert this light into electrical nerve impulses sent to the brain.
11.The visual angle is best defined as the:
Answer: A
The visual angle is the angle that an object (or its size) subtends at the eye; it determines the apparent size of the object as perceived.
12.For a normal human eye, the least distance of distinct vision (near point) is approximately:
Answer: D
The standard near point (least distance of distinct vision) for a normal eye is taken as 25 cm.
13.Accommodation is the ability of the eye lens to change its focal length (curvature) so that images of objects at different distances are focused sharply on the retina.
Answer: True
The ciliary muscles change the curvature (and hence focal length) of the crystalline lens, enabling clear focus over a range of object distances.
14.The far point of a normal eye is at ______, while its near point is about 25 cm.
Answer: infinity
A normal eye can focus on very distant objects (far point at infinity) as well as objects as close as 25 cm (near point).
15.In myopia (short-sightedness), the image of a distant object forms:
Answer: B
In myopia, the eyeball is too long or the lens/cornea too strongly curved, so parallel rays from distant objects converge in front of the retina.
16.Myopia (short-sightedness) is corrected using a:
Answer: C
A diverging lens spreads out the incoming rays slightly before they reach the eye's own lens, moving the focus point back onto the retina.
17.Hypermetropia (long-sightedness) is corrected using a:
Answer: A
A converging lens adds extra convergence to the light before it enters the eye, bringing the focus forward onto the retina instead of behind it.
18.A myopic person has a far point of 2.0 m. What power of corrective lens is needed to enable them to see very distant objects clearly?
Answer: A
The lens must form a virtual image of a distant object (u = ∞) at the far point (v = −2.0 m). Then 1/f = 1/v = 1/(−2.0), so f = −2.0 m and P = 1/f = −0.5 D.
19.A hypermetropic person has a near point of 100 cm instead of the normal 25 cm. What power of lens is required to allow them to read a book at 25 cm?
Answer: C
1/f = 1/v − 1/u = 1/(−1.0) − 1/(−0.25) = −1 + 4 = 3, so f = 1/3 m and P = +3 D (a converging lens).
20.Astigmatism is mainly caused by:
Answer: B
Astigmatism results from the cornea (or lens) having different curvatures along different planes, so light in different planes focuses at different points.
21.Astigmatism is corrected using a:
Answer: D
A cylindrical lens has different focal powers in different planes, compensating for the unequal curvature that causes astigmatism.
22.Myopia (short-sightedness) is corrected using a converging (convex) lens.
Answer: False
Myopia is corrected with a diverging (concave) lens, which reduces the eye's excessive converging power so images focus on the retina rather than in front of it.
23.A person suffering from hypermetropia has a near point that is ______ than the normal 25 cm.
Answer: farther (greater)
In hypermetropia, the near point recedes farther from the eye than the normal 25 cm, making close objects appear blurred.
24.Myopia can be caused by:
Answer: D
Myopia arises when the eyeball is elongated and/or the cornea/lens system is too strongly converging, both of which cause the image to form in front of the retina.
25.A simple microscope (magnifying glass) consists of a single converging lens with the object placed:
Answer: B
Placing the object within the focal length of a converging lens produces a virtual, erect, magnified image, which is the principle of a simple microscope.
26.A simple microscope has a focal length of 5 cm. What is its magnifying power when the image is formed at the near point (D = 25 cm)?
Answer: B
M = 1 + D/f = 1 + 25/5 = 6.
27.For the same simple microscope (f = 5 cm), what is its magnifying power when the final image is formed at infinity (relaxed eye)?
Answer: D
M = D/f = 25/5 = 5, for normal adjustment with the image at infinity.
28.A compound microscope consists of:
Answer: C
A compound microscope uses two converging lenses: an objective with a very short focal length placed close to the object, and an eyepiece used like a simple magnifier to further magnify the objective's image.
29.In a compound microscope, the objective lens produces a linear magnification of 10, and the eyepiece produces an angular magnification of 5. What is the overall magnifying power of the microscope?
Answer: D
Overall magnifying power M = Mo × Me = 10 × 5 = 50.
30.In a compound microscope, the image formed by the objective lens (which then acts as the object for the eyepiece) is:
Answer: B
The objective lens forms a real, inverted, magnified image of the specimen; this image acts as the object for the eyepiece, which further magnifies it.
31.In a simple microscope, the image formed is virtual, erect, and magnified.
Answer: True
Since the object is placed within the focal length of the single converging lens, a virtual, erect, magnified image is produced.
32.The magnifying power of a simple microscope with the final image formed at infinity (normal adjustment) is given by M = ______.
Answer: D/f
Where D is the least distance of distinct vision (25 cm) and f is the focal length of the lens.
33.In an astronomical (refracting) telescope, the objective lens has a focal length that is:
Answer: D
The objective lens of an astronomical telescope has a long focal length compared to the eyepiece, which has a short focal length, to achieve high magnifying power (M = fo/fe).
34.An astronomical telescope has an objective of focal length 100 cm and an eyepiece of focal length 5 cm. What is its magnifying power in normal adjustment?
Answer: B
M = fo/fe = 100/5 = 20.
35.For an astronomical telescope in normal adjustment (final image at infinity), the separation between the objective and eyepiece lenses is equal to:
Answer: C
In normal adjustment, the objective forms its image at its own focal point, which coincides with the focal point of the eyepiece, so the tube length equals fo + fe.
36.In normal adjustment, the final image produced by an astronomical telescope is:
Answer: A
In normal adjustment, the astronomical telescope produces a virtual, inverted image located at infinity, allowing viewing with a relaxed eye.
37.A telescope has an objective of focal length 120 cm and a magnifying power of 24 in normal adjustment. What is the focal length of its eyepiece?
Answer: C
fe = fo/M = 120/24 = 5 cm.
38.A large-aperture objective lens is used in astronomical telescopes mainly to:
Answer: B
A larger objective aperture collects more light from faint distant objects and improves the telescope's resolving power, producing a brighter, more detailed image.
39.To increase the magnifying power of an astronomical telescope in normal adjustment, one can use an eyepiece of shorter focal length.
Answer: True
Since M = fo/fe, decreasing fe (for a fixed fo) increases the magnifying power M.
40.In an astronomical telescope, the lens nearer to the distant object being observed is called the ______.
Answer: objective (lens)
The objective lens collects light from the distant object and forms a real image, which the eyepiece then magnifies.
1.A force is best described as an agent that can:
Answer: D
A force can change a body's velocity (speed or direction) or deform it; it may act through contact or at a distance (e.g., gravity, magnetism).
2.The SI unit of force is the:
Answer: B
The newton (N) is the SI unit of force, defined as the force that gives a 1 kg mass an acceleration of 1 m/s².
3.Which of the following is a vector quantity?
Answer: C
Force has both magnitude and direction, making it a vector quantity, unlike mass, temperature, and energy, which are scalars.
4.Two forces of 3 N and 4 N act on a body at right angles to each other. What is the magnitude of their resultant?
Answer: A
By Pythagoras' theorem, R = √(3² + 4²) = √25 = 5 N.
5.Two perpendicular forces of 6 N and 8 N act on a body. What angle does the resultant make with the 6 N force?
Answer: C
tan θ = 8/6 = 1.333, so θ = tan⁻¹(1.333) ≈ 53.1° from the 6 N force.
6.The scalar (dot) product of two vectors A and B is given by A·B = |A||B|cos θ. If A and B are perpendicular, then A·B equals:
Answer: C
When θ = 90°, cos θ = 0, so the scalar product of two perpendicular vectors is zero.
7.The direction of the vector (cross) product of two vectors, A × B, is found using the:
Answer: D
The vector product A × B has magnitude |A||B|sin θ and points in the direction given by the right-hand rule, perpendicular to the plane of A and B.
8.The scalar product of two perpendicular vectors is zero.
Answer: True
A·B = |A||B|cos 90° = 0, since cos 90° = 0.
9.A physical quantity that has both magnitude and direction is called a ______ quantity.
Answer: vector
Examples include force, velocity, displacement, and momentum, all of which require a direction to be fully specified.
10.The moment (torque) of a force about a point is defined as the product of the force and the:
Answer: D
Moment of a force = Force × perpendicular distance from the pivot/point to the line of action of the force.
11.A force of 20 N is applied at a perpendicular distance of 0.5 m from a pivot. What is the moment of the force about the pivot?
Answer: A
Moment = F × d = 20 × 0.5 = 10 N·m.
12.The SI unit of the moment of a force is the:
Answer: A
Since moment = force × distance, its unit is newton-metre (N·m), numerically the same as the joule but representing a different physical quantity (torque, not energy).
13.By common convention in moments problems, a moment that tends to turn a body in the anticlockwise direction is usually taken as:
Answer: D
By convention (though the choice is arbitrary as long as it is applied consistently), anticlockwise moments are usually taken as positive and clockwise moments as negative.
14.The moment of a force about a point depends on the perpendicular distance from the point to the line of action of the force.
Answer: True
Moment = force × perpendicular distance, so the same force produces a larger or smaller moment depending on how far its line of action is from the pivot.
15.The principle of moments states that, for a body in rotational equilibrium about a point:
Answer: B
The principle of moments (for rotational/moment equilibrium): total clockwise moment about any point equals total anticlockwise moment about the same point.
16.A uniform beam pivoted at a point has a 10 N force acting clockwise at a perpendicular distance of 0.3 m from the pivot. What anticlockwise force at a perpendicular distance of 0.2 m is needed to balance the beam?
Answer: D
By the principle of moments: F × 0.2 = 10 × 0.3, so F = 3/0.2 = 15 N.
17.A couple consists of:
Answer: D
A couple is formed by two forces of equal magnitude, acting in opposite directions along parallel (non-collinear) lines of action, producing a pure turning effect with zero net force.
18.A couple is formed by two forces of 5 N each, separated by a perpendicular distance of 0.4 m. What is the torque (moment) of this couple?
Answer: D
Torque of a couple = one force × perpendicular distance between the forces = 5 × 0.4 = 2 N·m.
19.Unlike a single force, a couple acting on a rigid body produces:
Answer: C
The two forces of a couple are equal and opposite, so they cancel to give zero net force, but because they act along different lines, they produce a net turning effect (torque) that is the same about any point.
20.A couple has zero net force but produces a net turning effect (torque) on the body it acts upon.
Answer: True
This is the defining property of a couple: resultant force = 0, resultant moment ≠ 0.
21.Two equal, opposite, and parallel forces whose lines of action do not coincide form a ______.
Answer: couple
Such a pair of forces produces pure rotation (a torque) with no net translational force.
22.The first condition for the equilibrium of a rigid body requires that:
Answer: B
The first (translational) condition for equilibrium is ΣF = 0, meaning the vector sum of all external forces acting on the body is zero.
23.The second condition for the equilibrium of a rigid body requires that:
Answer: A
The second (rotational) condition for equilibrium is Στ = 0: the sum of all moments/torques about any chosen point must be zero.
24.A free body diagram is used to:
Answer: A
A free body diagram isolates the object of interest and shows all external forces (weight, normal reactions, tension, friction, applied forces, etc.) acting on it, used to analyse equilibrium or motion.
25.A uniform beam of weight 100 N and length 4 m rests horizontally on two supports at its ends. What is the reaction force at each support?
Answer: C
By symmetry, the weight acting at the centre is shared equally: since ΣF = 0, R_left + R_right = 100 N, and by symmetry each = 50 N.
26.A non-uniform beam of length 5 m carries a weight of 100 N at a point 2 m from its left end, and rests on supports at both ends. Using the principle of moments about the left end, find the reaction at the right support.
Answer: B
Taking moments about the left support: R_right × 5 = 100 × 2, so R_right = 200/5 = 40 N (and R_left = 100 − 40 = 60 N by ΣF = 0).
27.For a rigid body to be in complete static equilibrium, both the translational equilibrium condition (ΣF = 0) and the rotational equilibrium condition (Στ = 0) must be satisfied simultaneously.
Answer: True
A body could have zero net force but still rotate (if there is a net torque, e.g. a couple), or have zero net torque but still accelerate (if there is a net force); both conditions are needed for full equilibrium.
28.The condition ΣF = 0 (the vector sum of all forces on a body is zero) represents ______ equilibrium.
Answer: translational
This ensures the body has no net linear acceleration; it is one of the two conditions needed for complete equilibrium.
29.A body is in stable equilibrium if, when slightly displaced and released, it:
Answer: B
In stable equilibrium, a small displacement raises the centre of gravity, creating a restoring moment that returns the body to its original position when released.
30.A cone balanced on its apex is an example of which type of equilibrium?
Answer: B
A small displacement lowers the centre of gravity and moves it outside the base of support, so the cone topples further away rather than returning — this is unstable equilibrium.
31.A ball resting on a flat horizontal surface, when displaced slightly, stays in its new position without returning or moving further. This illustrates:
Answer: C
In neutral equilibrium, the height of the centre of gravity does not change on displacement, so there is no restoring or further-toppling moment, and the body simply remains in its new position.
32.The centre of gravity of a body is defined as the point:
Answer: C
The centre of gravity is the single point through which the resultant weight of the body can be considered to act, for the purposes of analysing equilibrium and moments.
33.For a uniform straight rod, the centre of gravity lies at:
Answer: B
Because the rod is uniform, its mass is distributed symmetrically, so its centre of gravity coincides with its geometric midpoint.
34.The point at which the total weight of a body appears to act is called the ______.
Answer: centre of gravity
This concept simplifies the analysis of forces and moments by allowing the entire weight to be treated as a single force acting at this point.
35.Stress is defined as:
Answer: A
Stress = Force/Area, measured in pascals (Pa) or N/m², and represents the internal restoring force per unit area within a deformed material.
36.Strain is defined as:
Answer: A
Strain = extension/original length; being a ratio of two lengths, it is dimensionless and has no units.
37.A wire of length 2.0 m and cross-sectional area 1.0 × 10⁻⁶ m² stretches by 0.5 mm under a load of 50 N. What is the Young's modulus of the wire material?
Answer: A
Stress = F/A = 50/1×10⁻⁶ = 5×10⁷ Pa. Strain = extension/length = 0.5×10⁻³/2.0 = 2.5×10⁻⁴. Y = stress/strain = 5×10⁷/2.5×10⁻⁴ = 2×10¹¹ Pa.
38.The essential difference between tensile stress and compressive stress is that:
Answer: B
Tensile stress arises from forces pulling a material apart (elongating it), while compressive stress arises from forces pushing it together (shortening it).
39.Beyond the elastic limit, a material does not return to its original shape and size after the deforming force is removed.
Answer: True
Stretching (or compressing) a material beyond its elastic limit causes permanent (plastic) deformation, so it does not fully recover its original dimensions once the force is removed.
40.Young's modulus is defined as the ratio of (tensile or compressive) ______ to strain, within the elastic limit of the material.
Answer: stress
Y = stress/strain, and it remains constant for a given material as long as the deformation stays within the elastic limit (Hooke's law region).
1.According to the definition of mechanical work, W = Fd cosθ, what does θ represent?
Answer: D
θ is the angle between the applied force vector and the displacement vector; work is the component of force along the displacement multiplied by the displacement.
2.A force of 20 N pulls a box a distance of 5 m in the direction of the force. How much work is done?
Answer: A
W = Fd cosθ = 20 × 5 × cos0° = 100 J.
3.A 10 N force acts on an object, moving it 4 m at an angle of 60° to the force. What is the work done?
Answer: C
W = Fd cosθ = 10 × 4 × cos60° = 40 × 0.5 = 20 J.
4.The SI unit of work, the joule, is equivalent to which combination of base units?
Answer: C
Work is force times distance, so 1 joule = 1 newton-metre (N·m).
5.What is the gravitational potential energy of a 2 kg object raised 5 m above the ground (g = 10 m/s²)?
Answer: D
GPE = mgh = 2 × 10 × 5 = 100 J.
6.A spring with spring constant 200 N/m is compressed by 0.1 m. What elastic potential energy is stored in it?
Answer: C
Elastic PE = ½kx² = ½ × 200 × (0.1)² = ½ × 200 × 0.01 = 1 J.
7.A machine does 500 J of work in 10 seconds. What is its power output?
Answer: A
P = W/t = 500/10 = 50 W.
8.The watt, the SI unit of power, is equivalent to which of the following?
Answer: C
Power is the rate of doing work, so 1 watt = 1 joule per second (J/s).
9.A force acts exactly perpendicular to an object's displacement. How much work does this force do on the object?
Answer: C
When θ = 90°, cosθ = 0, so W = Fd cosθ = 0; a perpendicular force does no work.
10.The principle of conservation of mechanical energy states that in the absence of non-conservative forces such as friction, the total of which two quantities remains constant?
Answer: A
With no friction or air resistance, KE + PE remains constant as energy simply converts between the two forms.
11.A ball is dropped from rest from a height of 20 m (g = 10 m/s², ignore air resistance). What is its speed just before hitting the ground?
Answer: B
Using conservation of energy, mgh = ½mv², so v = √(2gh) = √(2×10×20) = √400 = 20 m/s.
12.In a swinging pendulum with no air resistance, at the lowest point of the swing the energy of the bob is:
Answer: B
At the lowest point, all the gravitational potential energy lost has been converted into kinetic energy.
13.Linear momentum of a body is defined by which formula?
Answer: D
Linear momentum p is the product of mass and velocity, p = mv.
14.A 0.5 kg ball moves with a velocity of 20 m/s. What is its momentum?
Answer: B
p = mv = 0.5 × 20 = 10 kg·m/s.
15.Impulse delivered to a body is related to momentum change by which equation?
Answer: A
Impulse equals the product of force and the time interval over which it acts, and equals the resulting change in momentum: J = FΔt = Δp.
16.A force of 50 N acts on an object for 0.2 s. What impulse is delivered?
Answer: A
J = FΔt = 50 × 0.2 = 10 N·s.
17.An impulse of 10 kg·m/s is applied to a 2 kg object initially at rest. What final velocity does it acquire?
Answer: D
J = Δp = mΔv, so Δv = J/m = 10/2 = 5 m/s.
18.The law of conservation of linear momentum applies strictly to which type of system?
Answer: C
Total momentum of a system is conserved only when the net external force acting on it is zero (an isolated system).
19.What defines an elastic collision between two bodies?
Answer: C
In a perfectly elastic collision, both total momentum and total kinetic energy of the system are conserved.
20.In an inelastic collision between two bodies, which statement is correct?
Answer: B
In inelastic collisions momentum is always conserved for an isolated system, but some kinetic energy is converted to heat, sound, or deformation.
21.What is the defining feature of a perfectly inelastic collision?
Answer: D
In a perfectly inelastic collision the colliding objects stick together and move as one body with a common final velocity.
22.A 2 kg trolley moving at 3 m/s collides and sticks to a stationary 1 kg trolley. What is their common velocity after collision?
Answer: A
By conservation of momentum: m1v1 + m2v2 = (m1+m2)v → (2×3 + 1×0) = 3v → v = 6/3 = 2 m/s.
23.Two identical trolleys undergo a head-on elastic collision, with trolley A moving and trolley B initially at rest. What happens to their velocities after collision?
Answer: B
For an elastic collision between equal masses where one is initially at rest, the moving object stops and transfers all its velocity to the object it strikes.
24.In a glancing (two-dimensional) collision, how must momentum conservation be applied?
Answer: B
In 2D collisions, momentum is conserved independently along each perpendicular axis, so the x-components and y-components are each conserved separately.
25.Rocket propulsion is best explained using which physical principle?
Answer: B
A rocket expels exhaust gases backward; by conservation of momentum, the rocket itself gains forward momentum equal and opposite to that of the ejected gas.
26.Why does a rocket accelerate forward as it burns fuel and ejects exhaust gas backward?
Answer: A
The rocket exerts a backward force on the exhaust gas, and by Newton's third law the gas exerts an equal, opposite (forward) force on the rocket.
27.Which quantity is NOT conserved in a perfectly inelastic collision between two isolated objects?
Answer: D
Kinetic energy is lost (converted to heat, sound, deformation) in inelastic collisions, while momentum, mass, and total energy remain conserved.
28.The work-energy theorem states that the net work done on an object equals:
Answer: D
The work-energy theorem: net work done on a body equals its change in kinetic energy, W_net = ΔKE.
29.What is the kinetic energy of a 4 kg object moving at 5 m/s?
Answer: A
KE = ½mv² = ½ × 4 × 5² = ½ × 4 × 25 = 50 J.
30.A 1000 kg car travelling at 20 m/s brakes uniformly and stops over a distance of 50 m. What is the average braking force?
Answer: B
KE lost = ½×1000×20² = 200,000 J = Fd, so F = 200000/50 = 4000 N.
31.In a perfectly elastic collision, total kinetic energy of the system is conserved.
Answer: True
By definition, elastic collisions conserve both total momentum and total kinetic energy.
32.Impulse and momentum are measured in the same units.
Answer: True
Impulse equals a change in momentum, so both are measured in kg·m/s (equivalently N·s).
33.Momentum is a scalar quantity with no direction.
Answer: False
Momentum p = mv is a vector quantity; it has both magnitude and direction, following the direction of velocity.
34.In a perfectly inelastic collision, the colliding bodies move with a common velocity immediately after impact.
Answer: True
This is the defining characteristic of a perfectly inelastic collision — the bodies stick together and move as one.
35.Total mechanical energy of a system remains constant even when friction acts within the system.
Answer: False
Friction is a non-conservative force that converts mechanical energy into heat, so mechanical energy is not conserved when friction acts.
36.The SI unit of power is the ______.
Answer: watt
Power is measured in watts (W), where 1 W = 1 J/s.
37.The law of conservation of momentum states that in the absence of a net external force, the total momentum of a system remains ______.
Answer: constant
With zero net external force, total momentum before and after any interaction stays the same (constant).
38.Rocket propulsion works based on the principle of conservation of ______.
Answer: momentum
The rocket and its ejected exhaust gases form an isolated system whose total momentum is conserved.
39.The elastic potential energy stored in a stretched or compressed spring of spring constant k and extension x is given by the formula ______.
Answer: ½kx² (E = ½kx²)
Elastic potential energy in a spring is E = ½kx², derived from the work done in stretching or compressing it.
40.A collision in which the total kinetic energy of the system is conserved is called a(n) ______ collision.
Answer: elastic
By definition, an elastic collision conserves both momentum and kinetic energy.
1.Electric current is defined by which relationship?
Answer: B
Electric current is the rate of flow of charge: I = Q/t, measured in amperes.
2.A charge of 10 C flows through a conductor in 5 s. What is the current?
Answer: C
I = Q/t = 10/5 = 2 A.
3.Electromotive force (e.m.f.) of a source is best defined as:
Answer: D
e.m.f. is the total energy supplied to each coulomb of charge by the source, including energy used to overcome internal resistance.
4.The terminal voltage V of a cell with e.m.f. ε, internal resistance r, delivering current I, is given by:
Answer: B
Some of the e.m.f. is used to drive current through the internal resistance, so terminal voltage V = ε − Ir.
5.A battery has e.m.f. 12 V and internal resistance 0.5 Ω. When it delivers a current of 2 A, what is its terminal voltage?
Answer: D
V = ε − Ir = 12 − (2×0.5) = 12 − 1 = 11 V.
6.Why does the terminal voltage of a battery drop as it supplies more current?
Answer: A
Part of the e.m.f. is used up overcoming the internal resistance (voltage drop = Ir), leaving less voltage available at the terminals.
7.What is the formula for the total (equivalent) resistance of resistors R1, R2, and R3 connected in series?
Answer: A
For resistors in series, the equivalent resistance is simply the sum of the individual resistances.
8.Three resistors of 2 Ω, 3 Ω, and 5 Ω are connected in series. What is the total resistance?
Answer: A
In series: R = 2 + 3 + 5 = 10 Ω.
9.What is the formula for the equivalent resistance of two resistors R1 and R2 connected in parallel?
Answer: A
For resistors in parallel, the reciprocal of the equivalent resistance equals the sum of the reciprocals of each resistance.
10.Two resistors of 4 Ω each are connected in parallel. What is their equivalent resistance?
Answer: D
1/R = 1/4 + 1/4 = 2/4 = 1/2, so R = 2 Ω.
11.Resistors of 6 Ω and 3 Ω are connected in parallel. What is the equivalent resistance?
Answer: D
1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2, so R = 2 Ω.
12.In a series circuit containing several resistors connected to a battery, which quantity is the same through every resistor?
Answer: A
In a series circuit, there is only one path for charge, so the same current flows through every component.
13.In a parallel circuit, which quantity is the same across every branch?
Answer: C
Each branch of a parallel circuit is connected directly across the same two nodes, so the potential difference across each branch is equal.
14.When identical cells are connected in series (same polarity), what happens to the total e.m.f. of the combination?
Answer: B
Cells connected in series with matching polarity add their e.m.f.s: total e.m.f. = ε1 + ε2 + ε3 + ...
15.Three identical 1.5 V cells are connected in series. What is the total e.m.f. of the combination?
Answer: C
Total e.m.f. = 1.5 + 1.5 + 1.5 = 4.5 V.
16.What is the main advantage of connecting several identical cells in parallel rather than using a single cell?
Answer: C
Parallel identical cells keep the same overall e.m.f. as one cell but reduce the combined internal resistance, allowing a larger current to be supplied.
17.Kirchhoff's current law (junction rule) states that at any junction in a circuit:
Answer: B
Kirchhoff's current law is a statement of conservation of charge: total current into a junction equals total current out of it.
18.Kirchhoff's voltage law (loop rule) states that around any closed loop in a circuit:
Answer: B
Kirchhoff's voltage law reflects conservation of energy: the sum of e.m.f.s around a loop equals the sum of potential drops around that same loop.
19.A circuit has two cells connected in opposition: e.m.f. 10 V and e.m.f. 6 V, each with internal resistance 1 Ω, in series with an external resistor of 2 Ω. What current flows in the circuit?
Answer: A
Net e.m.f. = 10 − 6 = 4 V; total resistance = 1 + 1 + 2 = 4 Ω; I = V/R = 4/4 = 1 A.
20.A single-loop circuit has a cell of e.m.f. 9 V, internal resistance 1 Ω, connected to an external resistor of 2 Ω. What current flows in the circuit?
Answer: A
Total resistance = r + R = 1 + 2 = 3 Ω; I = ε/R_total = 9/3 = 3 A.
21.Using the circuit in the previous question (ε = 9 V, r = 1 Ω, R = 2 Ω, I = 3 A), what is the terminal voltage of the cell?
Answer: B
V = ε − Ir = 9 − (3×1) = 6 V, which also equals IR = 3×2 = 6 V across the external resistor.
22.A current of 2 A flows through a resistor of 5 Ω. What power is dissipated in the resistor?
Answer: C
P = I²R = 2² × 5 = 4 × 5 = 20 W.
23.A source of e.m.f. 12 V supplies a current of 2 A to a circuit. What total power is delivered by the source?
Answer: D
Power delivered by the source, P = εI = 12 × 2 = 24 W.
24.Maximum power is transferred from a source to an external load when:
Answer: D
The maximum power transfer theorem states that maximum power is delivered to the load when the load resistance equals the source's internal resistance.
25.If the external (load) resistance of a circuit is reduced to zero (a short circuit), what determines the maximum current that flows?
Answer: C
With R = 0, the only opposition to current is the internal resistance, so the short-circuit current is I = ε/r, the maximum current the source can supply.
26.An ammeter used to measure current in a circuit is designed to have:
Answer: A
An ammeter is connected in series in the current path and must have very low resistance so it does not significantly alter the current being measured.
27.A voltmeter used to measure potential difference across a component is designed to have:
Answer: B
A voltmeter is connected in parallel across a component and must have very high resistance so it draws negligible current from the circuit.
28.When applying Kirchhoff's voltage law while tracing a loop in the same direction as the assumed current through a resistor, the potential change across that resistor is treated as a:
Answer: B
By the standard sign convention, moving through a resistor in the direction of current flow gives a potential drop, taken as −IR in the loop equation.
29.Three resistors of 2 Ω, 3 Ω, and 6 Ω are connected in parallel. What is their equivalent resistance?
Answer: D
1/R = 1/2 + 1/3 + 1/6 = 3/6 + 2/6 + 1/6 = 6/6 = 1, so R = 1 Ω.
30.A 2 Ω resistor is connected in series with a parallel combination of two 4 Ω resistors. What is the total resistance of the network?
Answer: C
The two 4 Ω resistors in parallel give 2 Ω; adding the series 2 Ω resistor gives a total of 2 + 2 = 4 Ω.
31.The terminal voltage of a discharging battery is always greater than its e.m.f.
Answer: False
Terminal voltage V = ε − Ir is always less than the e.m.f. when current flows, due to the internal resistance drop.
32.Kirchhoff's current law is a direct consequence of the law of conservation of electric charge.
Answer: True
Since charge cannot accumulate at a junction, the current flowing in must equal the current flowing out, which is a statement of charge conservation.
33.The equivalent resistance of resistors connected in series is always greater than the largest individual resistance in the combination.
Answer: True
Since series resistance is the sum of all resistances, it must exceed any single one of them.
34.Connecting several identical cells in parallel increases the total e.m.f. of the combination beyond that of a single cell.
Answer: False
Identical cells in parallel give the same e.m.f. as a single cell; what increases is the maximum current the combination can safely supply.
35.Kirchhoff's voltage law is based on the principle of conservation of energy.
Answer: True
Since electric potential is related to energy per unit charge, the loop rule reflects the fact that energy supplied by e.m.f. sources equals energy dissipated around a closed loop.
36.The SI unit of electromotive force is the ______.
Answer: volt
Electromotive force, like potential difference, is measured in volts (V).
37.Kirchhoff's ______ law (junction rule) states that the algebraic sum of currents meeting at a junction is zero.
Answer: current
This is Kirchhoff's current law (also called the first law or junction rule).
38.The resistance that opposes current flow inside a battery or cell itself is called its ______ resistance.
Answer: internal
Internal resistance is the resistance within the source itself, causing a voltage drop when current flows.
39.For resistors connected in ______, the same current flows through each resistor, but the voltage divides between them.
Answer: series
In a series connection there is only one current path, so current is common while voltage divides across each resistor.
40.The terminal voltage V of a cell of e.m.f. ε and internal resistance r delivering current I is given by V = ε − ______.
Answer: Ir
The voltage dropped across the internal resistance, Ir, is subtracted from the e.m.f. to give the terminal voltage.
1.Which of the following is classified as a renewable energy source?
Answer: D
Solar energy is continuously replenished by the sun and does not get depleted, making it renewable, unlike fossil fuels.
2.Which of the following is classified as a non-renewable energy source?
Answer: A
Coal is a fossil fuel formed over millions of years and is consumed much faster than it can naturally form, making it non-renewable.
3.What is currently the largest source of electricity generation in Rwanda?
Answer: C
Rwanda's electricity generation relies primarily on hydropower plants harnessing the country's rivers, supplemented by methane gas, solar, and thermal sources.
4.Which unique energy resource is extracted from Lake Kivu and used for electricity generation in Rwanda?
Answer: B
Lake Kivu contains large dissolved reserves of methane gas, which Rwanda extracts and uses to generate electricity.
5.Which is a major advantage of solar energy as a power source?
Answer: D
Solar panels generate electricity without burning fuel, so they produce no direct greenhouse gas emissions during operation.
6.Which is a major disadvantage of solar energy?
Answer: C
Solar power generation depends on sunlight, so output varies with weather, time of day, and season, making it intermittent.
7.Which is a key advantage of hydropower as an energy source?
Answer: A
Hydropower plants use flowing water and require no fuel purchases after construction, providing a reliable and relatively low-cost source of continuous power.
8.Which is a key disadvantage of hydropower?
Answer: C
Building large dams can flood land, displace people, and alter river ecosystems, which are significant environmental and social costs.
9.What is an advantage of wind energy?
Answer: B
Wind turbines convert wind's kinetic energy into electricity without burning fuel, giving low emissions and low running costs after installation.
10.What is a disadvantage of wind energy?
Answer: C
Wind turbines only generate power when wind speeds are sufficient, so output is variable and unreliable at low or excessive wind speeds.
11.Geothermal energy is best described as energy derived from:
Answer: B
Geothermal energy harnesses heat generated within the Earth, often accessed through hot springs, steam, or drilled wells.
12.Biomass energy is obtained from which of the following?
Answer: A
Biomass energy comes from organic materials like wood, agricultural residues, and animal waste, which can be burned or converted into fuel.
13.Fossil fuels such as coal, oil, and natural gas are classified as non-renewable because:
Answer: C
Fossil fuels take millions of years to form from ancient organic material, so at current consumption rates they cannot be replenished within a human timescale.
14.Nuclear energy is generated in a power plant primarily through which process?
Answer: A
Nuclear power plants split (fission) heavy nuclei, typically uranium-235, releasing large amounts of heat used to generate electricity.
15.Which is an advantage of nuclear energy?
Answer: C
Nuclear fission releases enormous amounts of energy per unit mass of fuel compared to fossil fuels, making it highly energy-dense.
16.Which is a significant disadvantage of nuclear energy?
Answer: A
Nuclear power generates radioactive waste requiring careful, long-term storage, and accidents (though rare) can have severe consequences.
17.Burning coal in a power station mainly contributes to environmental damage by releasing:
Answer: A
Coal combustion releases carbon dioxide (a greenhouse gas) along with sulfur dioxide and particulates that cause air pollution and acid rain.
18.In a hydroelectric power plant, what is the correct sequence of energy conversion?
Answer: A
Water stored at height has gravitational potential energy, which converts to kinetic energy as it falls and turns turbines, which generators then convert to electrical energy.
19.In a solar photovoltaic panel, what type of energy conversion takes place?
Answer: B
Photovoltaic cells convert light (solar radiation) directly into electrical energy through the photovoltaic effect.
20.In a typical fossil-fuel thermal power plant, what is the correct order of energy conversion?
Answer: B
Burning fuel releases chemical energy as heat, which boils water to produce steam that turns a turbine (mechanical energy), which a generator converts to electrical energy.
21.Why is electricity transmitted over long distances at very high voltages?
Answer: B
For a fixed power, increasing voltage reduces the current needed; since power loss in the lines is I²R, a lower current greatly reduces energy wasted as heat.
22.The network of cables, transformers, and substations used to carry electricity from power stations to consumers is called the:
Answer: A
The national grid is the interconnected transmission and distribution network that delivers electrical energy from generating stations to homes and industries.
23.In terms of reliability, which type of energy source generally provides the most continuous, on-demand power output?
Answer: D
Hydropower with a steady water supply and fossil fuel plants can generate continuously on demand, whereas solar and wind depend on variable weather conditions.
24.Widespread use of firewood and charcoal as household energy sources in developing regions is most closely linked to which environmental problem?
Answer: B
Heavy reliance on firewood and charcoal for cooking and heating drives tree-cutting faster than regrowth, leading to deforestation.
25.A country that must import petroleum products because it lacks domestic oil reserves faces which economic consequence?
Answer: B
Importing fuel means spending foreign currency and being vulnerable to volatile international oil prices, which raises energy costs and affects the trade balance.
26.Which of the following is an effective energy conservation practice for a household?
Answer: D
Using efficient appliances such as LED bulbs and switching off devices when not needed reduces unnecessary energy consumption.
27.Sustainable energy development is best defined as:
Answer: C
Sustainable development balances current energy needs with the responsibility to preserve resources and environmental quality for future generations.
28.As part of its future energy strategy, Rwanda has been expanding which type of energy solution to improve rural electricity access?
Answer: D
Rwanda has promoted off-grid and mini-grid solar solutions, alongside grid extension, to increase electricity access in rural and remote areas.
29.Which characteristic makes an energy source described as 'reliable'?
Answer: D
A reliable energy source can consistently supply power when needed, without being overly dependent on unpredictable conditions.
30.Compared with fossil fuel power plants, why are renewable sources like solar and wind generally considered more environmentally friendly during operation?
Answer: D
Solar and wind systems convert natural energy flows into electricity without combustion, so they emit little to no direct greenhouse gases during operation.
31.Solar energy is classified as a non-renewable source of energy.
Answer: False
Solar energy is renewable because sunlight is continuously supplied by the sun and is not depleted by use.
32.Methane gas extracted from Lake Kivu is used to generate electricity in Rwanda.
Answer: True
Rwanda has developed methane extraction and power generation projects on Lake Kivu, converting the dissolved gas into electricity.
33.Burning fossil fuels contributes to climate change through the release of greenhouse gases such as carbon dioxide.
Answer: True
Fossil fuel combustion releases carbon dioxide, a major greenhouse gas responsible for global warming and climate change.
34.Hydropower currently supplies the largest share of Rwanda's electricity generation.
Answer: True
Rwanda's power generation mix has historically been dominated by hydropower plants on its rivers, alongside growing methane gas, solar, and thermal contributions.
35.Nuclear power plants generate electricity without producing any waste products.
Answer: False
Nuclear power plants produce radioactive waste that must be carefully managed and stored for long periods.
36.Energy sources that can be naturally replenished within a short period of time are called ______ energy sources.
Answer: renewable
Renewable energy sources, such as solar, wind, and hydropower, are naturally replenished and do not get permanently depleted.
37.______ energy is harnessed from heat stored beneath the Earth's surface.
Answer: Geothermal
Geothermal energy comes from the natural heat within the Earth, accessed via hot springs, steam vents, or drilled wells.
38.In Rwanda, gas dissolved in Lake ______ is extracted and used as a resource for electricity generation.
Answer: Kivu
Lake Kivu holds significant dissolved methane gas reserves that Rwanda taps for power generation.
39.Reducing wasteful use of energy resources and using them wisely so they last longer is called energy ______.
Answer: conservation
Energy conservation refers to reducing unnecessary energy use to preserve resources and reduce costs and environmental impact.
40.Electrical energy is transmitted over long distances at high ______ in order to minimize power losses in the transmission lines.
Answer: voltage
Transmitting at high voltage reduces the current needed for a given power, which minimizes I²R losses in the cables.
1.What is projectile motion?
Answer: C
Projectile motion is the two-dimensional motion of an object launched into the air and acted on only by gravity (air resistance ignored), producing a curved (parabolic) path.
2.After a projectile is launched (ignoring air resistance), which force continues to act on it?
Answer: D
Once launched, the only force acting on an ideal projectile is the weight (gravity) pulling it downward.
3.In horizontal projectile motion, the horizontal component of velocity:
Answer: C
There is no horizontal force (air resistance ignored), so horizontal velocity stays constant throughout the flight.
4.In horizontal projectile motion, the vertical component of velocity:
Answer: B
Gravity acts vertically downward, causing the vertical velocity to increase uniformly according to v_y = gt.
5.A ball is projected horizontally from a cliff of height 20 m (g = 10 m/s²). How long does it take to hit the ground?
Answer: B
Using h = ½gt² → 20 = ½(10)t² → t² = 4 → t = 2 s.
6.A stone is thrown horizontally with speed 15 m/s from a height of 20 m (g = 10 m/s²). What horizontal distance does it travel before landing?
Answer: C
Time of flight t = √(2h/g) = √(4) = 2 s. Horizontal range x = v·t = 15 × 2 = 30 m.
7.An object is projected horizontally from a height of 45 m (g = 10 m/s²). Find the time of flight.
Answer: B
t = √(2h/g) = √(2×45/10) = √9 = 3 s.
8.For a projectile launched horizontally from height h, the time of flight is given by:
Answer: D
Since the vertical motion starts from rest and falls height h under gravity, h = ½gt², giving t = √(2h/g).
9.The path traced by a projectile launched at an angle to the horizontal is:
Answer: C
Combining uniform horizontal motion with uniformly accelerated vertical motion produces a parabolic trajectory.
10.The time of flight of a projectile launched at angle θ with initial speed v is given by:
Answer: B
The projectile returns to launch height when the vertical displacement is zero, giving T = 2v sinθ/g.
11.A projectile is launched at 20 m/s at 30° to the horizontal (g = 10 m/s²). Find its time of flight.
Answer: D
T = 2v sinθ/g = 2(20)(0.5)/10 = 2 s.
12.The maximum height reached by a projectile launched at angle θ with speed v is given by:
Answer: A
At maximum height the vertical velocity is zero; using v_y² = (v sinθ)² − 2gH = 0 gives H = v²sin²θ/2g.
13.A projectile is launched at 20 m/s at 30° to the horizontal (g = 10 m/s²). Find its maximum height.
Answer: D
H = v²sin²θ/2g = (20²)(0.5²)/(2×10) = (400×0.25)/20 = 5 m.
14.The horizontal range of a projectile launched at angle θ with speed v is given by:
Answer: C
Range is horizontal distance covered during the time of flight, R = v cosθ × T = v²sin2θ/g.
15.A projectile is launched at 20 m/s at 30° to the horizontal (g = 10 m/s²). Find its horizontal range (sin60° ≈ 0.87).
Answer: B
R = v²sin2θ/g = (400 × sin60°)/10 = (400 × 0.87)/10 ≈ 34.6 m.
16.For a given launch speed, the angle of projection that gives the maximum horizontal range (on level ground) is:
Answer: A
Range R = v²sin2θ/g is maximum when sin2θ = 1, i.e. 2θ = 90°, so θ = 45°.
17.A ball launched at 30° and another launched at 60° with the same initial speed will have:
Answer: D
Angles that are complementary (30° and 60°) give sin2θ the same value, so the ranges are equal, though heights and times of flight differ.
18.At the highest point of a projectile's trajectory (launched at an angle), the vertical component of velocity is:
Answer: D
At maximum height the projectile momentarily stops rising, so its vertical velocity component is zero.
19.At the highest point of its trajectory, the speed of a projectile launched at an angle (other than 90°) is:
Answer: A
Only the vertical velocity becomes zero at the top; the horizontal component v cosθ remains, so the speed at the top equals v cosθ.
20.Ignoring air resistance, which quantity remains constant throughout the entire flight of a projectile launched at an angle?
Answer: B
With no horizontal force, the horizontal velocity component stays constant; vertical velocity, speed and kinetic energy all change.
21.A footballer kicks a ball so that it follows a curved path through the air before landing. This is an example of:
Answer: A
The ball undergoes projectile motion, launched at an angle and acted on only by gravity.
22.In military applications, understanding projectile motion equations helps in:
Answer: D
Range and time-of-flight equations of projectile motion allow calculation of the angle and speed needed for a shell to hit a target at a known distance.
23.A decorative water fountain jet leaves a nozzle at an angle and lands some distance away. This is best explained using:
Answer: A
The water jet follows a curved path under gravity, exactly like any projectile launched at an angle.
24.In designing an irrigation sprinkler, engineers adjust the nozzle angle mainly to:
Answer: A
Since range depends on launch angle (maximum at 45°) and speed, engineers choose the angle to control how far the water is thrown.
25.A conical pendulum consists of a bob attached to a string that:
Answer: A
In a conical pendulum, the bob moves in a horizontal circle at constant speed while the string traces the surface of a cone.
26.For a conical pendulum of string length L making angle θ with the vertical, the vertical equilibrium condition is:
Answer: C
The vertical component of tension balances the weight of the bob: T cosθ = mg.
27.In a conical pendulum, the horizontal component of the string's tension provides:
Answer: B
T sinθ is the unbalanced horizontal component of tension, which supplies the centripetal force mv²/r directed toward the center of the circle.
28.The banking angle θ of a curved road of radius r for a vehicle moving at speed v (ignoring friction) is given by:
Answer: C
Resolving forces on a banked, frictionless curve gives tanθ = v²/(rg), the ideal banking angle for speed v on radius r.
29.A car travels at 20 m/s around a banked curve of radius 100 m (g = 10 m/s²). What is the ideal banking angle?
Answer: B
tanθ = v²/rg = 400/(100×10) = 0.4, so θ = tan⁻¹(0.4) ≈ 21.8°.
30.The main purpose of banking a road at a curve is to:
Answer: A
Banking tilts the road so part of the normal reaction points toward the center of the curve, supplying centripetal force and reducing dependence on friction, especially at higher speeds.
31.The horizontal component of a projectile's velocity remains constant throughout its flight, ignoring air resistance.
Answer: True
With no horizontal forces acting, the horizontal velocity component does not change during the flight.
32.The time of flight of a projectile launched horizontally from a height depends on its initial horizontal speed.
Answer: False
Time of flight for horizontal projection depends only on the height and g, t = √(2h/g); horizontal speed only affects the range, not the time.
33.A conical pendulum's bob moves with constant speed along a horizontal circular path.
Answer: True
In steady conical pendulum motion, the bob moves in a horizontal circle at constant angular and linear speed.
34.The ideal banking angle of a road depends on the mass of the vehicle using it.
Answer: False
In tanθ = v²/(rg), mass cancels out, so the ideal banking angle does not depend on the vehicle's mass.
35.At the top of its trajectory, a projectile launched at an angle (other than 90°) has zero total velocity.
Answer: False
Only the vertical velocity component is zero at the top; the horizontal component v cosθ is still non-zero, so the total velocity is not zero.
36.The curved path traced by a projectile is called a ______.
Answer: parabola
Combining constant horizontal velocity with uniformly accelerated vertical motion produces a parabolic path.
37.For a projectile launched horizontally from height h, the time of flight is given by t = ______.
Answer: √(2h/g)
This comes from the vertical free-fall equation h = ½gt² solved for t.
38.The formula for the ideal banking angle of a road is tanθ = ______.
Answer: v²/rg
This is derived by resolving the normal reaction and weight to supply the centripetal force on a frictionless banked curve.
39.In uniform circular motion, the net force directed toward the center of the circle is called the ______ force.
Answer: centripetal
The centripetal force continuously changes the direction of velocity, keeping the object moving in a circle.
40.For a projectile launched on level ground, the maximum horizontal range (for a given speed) is achieved at a launch angle of ______ degrees.
Answer: 45
Range R = v²sin2θ/g is maximum when sin2θ = 1, i.e. θ = 45°.
1.Coulomb's law states that the electrostatic force between two point charges is:
Answer: A
Coulomb's law: F = kq1q2/r², so force increases with charge magnitude and decreases with the square of separation.
2.The mathematical form of Coulomb's law is:
Answer: A
Coulomb's law is F = kq1q2/r², where k is Coulomb's constant.
3.Two point charges of 2 μC and 3 μC are separated by 0.1 m (k = 9×10⁹ N·m²/C²). Find the force between them.
Answer: D
F = kq1q2/r² = (9×10⁹)(2×10⁻⁶)(3×10⁻⁶)/(0.1)² = 9×10⁹×6×10⁻¹²/0.01 = 5.4 N.
4.Two equal charges of 4 μC each are placed 0.2 m apart (k = 9×10⁹ N·m²/C²). Find the force between them.
Answer: D
F = kq1q2/r² = (9×10⁹)(4×10⁻⁶)(4×10⁻⁶)/(0.2)² = 9×10⁹×1.6×10⁻¹¹/0.04 = 3.6 N.
5.The SI unit of electric charge is the:
Answer: C
Electric charge is measured in coulombs (C).
6.The magnitude of the charge on a single electron (elementary charge) is approximately:
Answer: B
The elementary charge e ≈ 1.6 × 10⁻¹⁹ C.
7.Two point charges will repel each other if they:
Answer: B
Like charges (both positive or both negative) repel; unlike charges attract.
8.The value of Coulomb's constant, k, in SI units is approximately:
Answer: C
Coulomb's constant k = 1/(4πε₀) ≈ 9 × 10⁹ N·m²/C².
9.If the distance between two point charges is doubled while the charges stay the same, the electrostatic force between them becomes:
Answer: D
Since F ∝ 1/r², doubling r reduces F by a factor of 2² = 4, so the new force is one quarter of the original.
10.Electric field intensity at a point is defined as:
Answer: A
Electric field intensity E = F/q, the force experienced per unit positive test charge.
11.The electric field intensity due to a point charge Q at distance r is given by:
Answer: A
E = kQ/r², derived from E = F/q using Coulomb's law.
12.A point charge of 5 μC produces an electric field at a distance of 0.2 m (k = 9×10⁹ N·m²/C²). Find the field strength.
Answer: D
E = kQ/r² = (9×10⁹)(5×10⁻⁶)/(0.2)² = 4.5×10⁴/0.04 = 1.125×10⁶ N/C.
13.The SI unit of electric field intensity can be expressed as:
Answer: D
Electric field intensity has units of newtons per coulomb, equivalent to volts per metre.
14.Electric field lines around an isolated positive point charge:
Answer: D
Field lines originate on positive charges and point radially outward, showing the direction of force on a positive test charge.
15.Electric field lines around an isolated negative point charge:
Answer: A
Field lines terminate on negative charges, so they point radially inward toward the negative charge.
16.The principle of superposition for electric fields states that the resultant field due to several charges is:
Answer: C
By superposition, each charge produces its own field independently, and the net field is the vector sum of all individual fields.
17.Two equal positive point charges are placed a fixed distance apart. The electric field at the midpoint between them is:
Answer: D
At the midpoint, each charge produces a field of equal magnitude but pointing away from itself (in opposite directions), so by superposition they cancel to zero.
18.Electric potential at a point is defined as:
Answer: B
Electric potential V = W/q, the work done per unit charge to bring a small positive test charge from infinity to that point.
19.The electric potential at a distance r from a point charge Q is given by:
Answer: C
V = kQ/r, obtained by integrating the electric field from infinity to distance r.
20.A point charge of 2 μC is at a distance of 0.5 m from a point P (k = 9×10⁹ N·m²/C²). Find the electric potential at P.
Answer: A
V = kQ/r = (9×10⁹)(2×10⁻⁶)/0.5 = 18,000/0.5 = 36,000 V.
21.Potential difference between two points in an electric field is defined as:
Answer: A
Potential difference is the work done per unit positive charge moved between two points, V = W/q.
22.The electric potential energy of two point charges q1 and q2 separated by distance r is given by:
Answer: C
Electrostatic potential energy U = kq1q2/r, the work needed to assemble the two charges from infinite separation.
23.Charges of +1 μC and −2 μC are separated by 0.1 m (k = 9×10⁹ N·m²/C²). Find their electric potential energy.
Answer: B
U = kq1q2/r = (9×10⁹)(1×10⁻⁶)(−2×10⁻⁶)/0.1 = −0.018/0.1 = −0.18 J.
24.A capacitor is a device that mainly functions to:
Answer: C
A capacitor consists of two conductive plates separated by a dielectric and stores charge (and energy) when a potential difference is applied.
25.Capacitance of a capacitor is defined by the relation:
Answer: B
Capacitance C = Q/V, the charge stored per unit potential difference across the capacitor.
26.A capacitor stores a charge of 6 μC when the potential difference across it is 3 V. Find its capacitance.
Answer: A
C = Q/V = 6 μC / 3 V = 2 μF.
27.The energy stored in a charged capacitor of capacitance C at voltage V is given by:
Answer: B
Energy stored in a capacitor: U = ½CV² (equivalently ½QV or Q²/2C).
28.A 4 μF capacitor is charged to a potential difference of 10 V. How much energy is stored in it?
Answer: C
U = ½CV² = ½(4×10⁻⁶)(10)² = ½(4×10⁻⁶)(100) = 2×10⁻⁴ J.
29.In an RC circuit, the time constant τ = RC represents:
Answer: B
The time constant τ = RC characterizes the rate of exponential charging or discharging; after one time constant, about 63% of the change has occurred.
30.Which of the following is a practical application of capacitors?
Answer: B
Capacitors are widely used to store and quickly release energy (e.g., camera flashes) and to smooth out voltage fluctuations in power supply circuits.
31.The electric field inside a conductor in electrostatic equilibrium is zero.
Answer: True
Free charges in a conductor rearrange themselves until the internal electric field cancels out, giving zero net field inside at equilibrium.
32.Like electric charges attract each other.
Answer: False
Like charges repel each other; only unlike (opposite) charges attract.
33.The electric potential energy of two charges with the same sign is positive.
Answer: True
Since U = kq1q2/r and q1q2 > 0 when both charges have the same sign, the potential energy is positive.
34.The capacitance of a capacitor depends on the amount of charge currently stored on it.
Answer: False
Capacitance depends on the geometry of the plates (area, separation) and the dielectric between them, not on the charge or voltage applied.
35.Inserting a dielectric material between the plates of a capacitor increases its capacitance.
Answer: True
A dielectric reduces the effective electric field between the plates for a given charge, allowing more charge to be stored per volt, thus increasing capacitance.
36.The SI unit of capacitance is the ______.
Answer: farad
Capacitance is measured in farads (F), named after Michael Faraday.
37.The energy stored in a charged capacitor is given by the formula U = ______.
Answer: ½CV²
This is derived from the work done to charge the capacitor gradually against the rising voltage.
38.Coulomb's law constant k has an approximate value of ______ N·m²/C².
Answer: 9 × 10⁹
This constant equals 1/(4πε₀), where ε₀ is the permittivity of free space.
39.The process by which a charged capacitor loses its stored charge through a resistor is called ______.
Answer: discharging
During discharging, the charge and voltage on the capacitor decay exponentially with time constant τ = RC.
40.According to the principle of ______, the resultant electric field due to several point charges is the vector sum of the fields due to each individual charge.
Answer: superposition
This principle allows the net field of a charge distribution to be found by adding the individual field vectors.
1.Internal energy of a thermodynamic system is best described as:
Answer: A
Internal energy U is the sum of the microscopic kinetic energy (molecular motion) and potential energy (intermolecular forces) of all particles in the system.
2.Thermal energy (heat) transferred between two systems occurs due to:
Answer: A
Heat flows spontaneously from a region of higher temperature to one of lower temperature until thermal equilibrium is reached.
3.The work done by a gas expanding at constant pressure P through a volume change ΔV is:
Answer: B
At constant pressure, work done by the gas is W = PΔV, from the definition W = ∫P dV.
4.A gas expands at a constant pressure of 2 × 10⁵ Pa, and its volume increases by 0.01 m³. Find the work done by the gas.
Answer: B
W = PΔV = (2×10⁵)(0.01) = 2,000 J.
5.A gas at constant pressure of 1 × 10⁵ Pa expands from 0.02 m³ to 0.05 m³. Find the work done by the gas.
Answer: D
ΔV = 0.05 − 0.02 = 0.03 m³. W = PΔV = (1×10⁵)(0.03) = 3,000 J.
6.The first law of thermodynamics is expressed mathematically as:
Answer: A
The first law states that the increase in internal energy equals heat added to the system minus the work done by the system, ΔU = Q − W.
7.A system absorbs 500 J of heat and does 200 J of work on its surroundings. Find the change in internal energy.
Answer: D
ΔU = Q − W = 500 − 200 = 300 J.
8.A gas releases 300 J of heat to its surroundings while 100 J of work is done on it. Find the change in internal energy of the gas.
Answer: A
Heat released means Q = −300 J; work done on the gas means W = −100 J (work done by gas is negative). ΔU = Q − W = −300 − (−100) = −200 J.
9.In the first law of thermodynamics (ΔU = Q − W), the work W is taken as positive when:
Answer: C
By the standard convention used here, W is positive when the system (gas) expands and does work on its surroundings.
10.In the first law of thermodynamics, heat Q is taken as positive when:
Answer: C
Q is positive when heat flows into the system from the surroundings.
11.For an ideal gas, the relationship between the molar specific heat capacities at constant pressure (Cp) and constant volume (Cv) is:
Answer: B
Mayer's relation for an ideal gas states Cp − Cv = R, where R is the universal gas constant.
12.Cp is greater than Cv for an ideal gas because:
Answer: B
At constant pressure, part of the heat supplied goes into expansion work (PΔV) in addition to raising internal energy, so more heat per degree is needed compared to constant volume, where all the heat raises only the internal energy.
13.An isothermal process is one in which:
Answer: A
In an isothermal process, the system's temperature stays constant throughout, requiring heat exchange with a reservoir as the gas expands or is compressed.
14.For an ideal gas undergoing an isothermal process, the relationship between Q and W is:
Answer: D
Since internal energy of an ideal gas depends only on temperature, ΔU = 0 in an isothermal process, so from the first law Q = W.
15.An isochoric (isovolumetric) process is one in which:
Answer: B
In an isochoric process the gas is held at constant volume, so no work is done by or on the gas (W = 0).
16.A gas undergoes an isochoric process and absorbs 400 J of heat. Find the change in its internal energy.
Answer: D
At constant volume, W = 0, so ΔU = Q − W = 400 − 0 = 400 J.
17.An isobaric process is one in which:
Answer: C
In an isobaric process, the gas pressure stays constant while volume and temperature may change.
18.A gas expands isobarically at 1.5 × 10⁵ Pa, with its volume increasing by 0.02 m³, while absorbing 3,500 J of heat. Find the change in internal energy.
Answer: D
W = PΔV = (1.5×10⁵)(0.02) = 3,000 J. ΔU = Q − W = 3,500 − 3,000 = 500 J.
19.An adiabatic process is one in which:
Answer: A
An adiabatic process occurs in a thermally insulated system, so Q = 0.
20.For an ideal gas undergoing an adiabatic process, the change in internal energy is related to work by:
Answer: C
Since Q = 0 in an adiabatic process, the first law gives ΔU = Q − W = −W.
21.For an ideal gas undergoing a reversible adiabatic process, pressure and volume are related by:
Answer: B
The adiabatic condition for an ideal gas is PVᵞ = constant, where γ = Cp/Cv is the ratio of specific heats.
22.Which thermodynamic process involves absolutely no heat transfer between the system and its surroundings?
Answer: D
By definition, an adiabatic process has Q = 0, meaning no heat enters or leaves the system.
23.For an ideal gas, which process results in no change in internal energy?
Answer: C
Since internal energy of an ideal gas depends only on temperature, and temperature is constant in an isothermal process, ΔU = 0.
24.A heat engine is a device that:
Answer: B
A heat engine operates in cycles, absorbing heat from a hot reservoir, converting part of it into useful mechanical work, and rejecting the rest to a cold reservoir.
25.The Otto cycle is the idealized thermodynamic cycle that models the operation of:
Answer: A
The Otto cycle describes the ideal operation of spark-ignition petrol engines, where fuel-air mixture is ignited by a spark.
26.The Diesel cycle is the idealized thermodynamic cycle that models the operation of:
Answer: B
The Diesel cycle models compression-ignition engines, where fuel is injected into highly compressed hot air and ignites without a spark.
27.The idealized Otto cycle consists of:
Answer: C
The Otto cycle consists of two adiabatic processes (compression and expansion) and two constant-volume processes (heat addition and rejection).
28.The main difference between the Diesel cycle and the Otto cycle is that in the Diesel cycle, heat is added:
Answer: A
In the Diesel cycle, combustion (heat addition) occurs at constant pressure, unlike the constant-volume heat addition in the Otto cycle.
29.The efficiency of a heat engine is generally defined as:
Answer: C
Efficiency is the fraction of the absorbed heat converted into useful work: η = W/Qh = (Qh − Qc)/Qh = 1 − Qc/Qh.
30.A heat engine absorbs 1000 J of heat from a hot reservoir and rejects 600 J to a cold reservoir. Find its efficiency.
Answer: D
η = 1 − Qc/Qh = 1 − 600/1000 = 1 − 0.6 = 0.4 = 40%.
31.In an isothermal process, the internal energy of an ideal gas remains constant.
Answer: True
Since internal energy of an ideal gas depends only on temperature, and temperature does not change in an isothermal process, ΔU = 0.
32.In an adiabatic process, heat is exchanged freely between the system and its surroundings.
Answer: False
An adiabatic process is defined by Q = 0; the system is thermally insulated from its surroundings.
33.No heat engine operating between two reservoirs can have an efficiency of 100%.
Answer: True
Some heat must always be rejected to the cold reservoir in a cyclic heat engine, so the efficiency is always less than 100%.
34.For an ideal gas, the molar specific heat capacity at constant pressure (Cp) is greater than that at constant volume (Cv).
Answer: True
At constant pressure, additional heat is needed to also perform expansion work, so Cp > Cv, consistent with Cp − Cv = R.
35.In an isochoric process, the gas does work on its surroundings as it is heated.
Answer: False
Since volume does not change in an isochoric process, W = PΔV = 0; no work is done by or on the gas.
36.The first law of thermodynamics states that the change in internal energy is given by ΔU = ______.
Answer: Q − W
This expresses conservation of energy: heat added to a system either increases its internal energy or is used to do work.
37.A thermodynamic process that occurs at constant volume is called an ______ process.
Answer: isochoric (isovolumetric)
Because volume does not change, no work is done during this process (W = 0).
38.A thermodynamic process in which no heat enters or leaves the system is called an ______ process.
Answer: adiabatic
This occurs in a thermally insulated system, so Q = 0 and ΔU = −W.
39.The idealized thermodynamic cycle that models the operation of diesel (compression-ignition) engines is called the ______ cycle.
Answer: Diesel
In this cycle, heat is added at constant pressure, unlike the constant-volume heat addition of the Otto cycle.
40.For an ideal gas, the relationship between the specific heat capacities is Cp − Cv = ______.
Answer: R (the universal/molar gas constant)
This relation, known as Mayer's relation, accounts for the extra work done during constant-pressure heating.
1.An astronomical unit (AU) is defined as:
Answer: C
1 AU is the mean distance from the Earth to the Sun, approximately 1.496 × 10¹¹ m, and is used as a convenient unit for distances within the solar system.
2.A light year is a unit used to measure:
Answer: B
A light year is a distance unit, defined as the distance light travels in a vacuum in one year, about 9.46 × 10¹² km.
3.Which unit is most appropriate for expressing distances to stars outside the solar system?
Answer: B
Interstellar distances are enormous, so astronomers use light years (or parsecs) rather than kilometers for convenience.
4.According to the widely accepted theory of the origin of the solar system, it formed from:
Answer: B
The nebular hypothesis proposes that the solar system formed from the gravitational collapse of a giant rotating cloud of gas and dust called the solar nebula.
5.According to the nebular hypothesis, the Sun formed from:
Answer: B
As the solar nebula collapsed under gravity, most of the mass concentrated at the center, becoming hot and dense enough to form the Sun.
6.According to the nebular hypothesis, the planets formed by:
Answer: A
In the flattened, rotating protoplanetary disk around the young Sun, dust and gas particles gradually collided and stuck together (accretion) to form planetesimals and eventually planets.
7.A solar eclipse occurs when:
Answer: A
During a solar eclipse, the Moon comes between the Sun and Earth, casting its shadow on parts of Earth's surface.
8.A lunar eclipse occurs when:
Answer: A
During a lunar eclipse, the Earth lies between the Sun and the Moon, and the Moon passes through the Earth's shadow.
9.A solar eclipse can only occur during which phase of the Moon?
Answer: A
A solar eclipse requires the Moon to be between the Earth and Sun, which happens only at new moon, when the Moon's illuminated side faces away from Earth.
10.A lunar eclipse can only occur during which phase of the Moon?
Answer: D
A lunar eclipse requires the Earth to be between the Sun and Moon, which happens only at full moon.
11.Eclipses do not occur at every new moon and every full moon mainly because:
Answer: D
Because the Moon's orbital plane is tilted about 5° to the ecliptic, the Sun, Earth and Moon are usually not perfectly aligned, so eclipses occur only a few times a year.
12.The main types of solar eclipse are:
Answer: B
Solar eclipses are classified as total (Sun fully blocked), partial (Sun partly blocked), or annular (a ring of Sun visible around the Moon).
13.The main types of lunar eclipse are:
Answer: D
Lunar eclipses are classified as total (Moon fully in Earth's umbra), partial (Moon partly in the umbra), and penumbral (Moon only in the lighter penumbral shadow).
14.The phase of the Moon that occurs a few days after new moon, when a thin sliver of the Moon is illuminated and increasing, is called:
Answer: C
As the illuminated portion grows (waxes) from new moon toward first quarter, this thin, growing sliver is the waxing crescent.
15.The phase of the Moon between the first quarter and full moon, when more than half is illuminated and increasing, is called:
Answer: D
As illumination increases (waxes) past half (first quarter) toward full moon, more than half is lit; this phase is the waxing gibbous.
16.The phases of the Moon are caused by:
Answer: A
The Moon always has one half lit by the Sun; as it orbits Earth, the visible fraction of that lit half from Earth's perspective changes, producing phases.
17.The inner (terrestrial) planets of the solar system are:
Answer: B
The four planets closest to the Sun—Mercury, Venus, Earth, and Mars—are called terrestrial (inner) planets because they are small and rocky.
18.The outer (Jovian/gas giant) planets of the solar system are:
Answer: D
Jupiter, Saturn, Uranus, and Neptune lie beyond the asteroid belt and are large gas/ice giants, called outer or Jovian planets.
19.Compared to the outer planets, the inner (terrestrial) planets are generally:
Answer: C
Terrestrial planets are relatively small, made of rock and metal, and have high average densities compared to the gas giants.
20.Compared to the inner planets, the outer (Jovian) planets are generally:
Answer: C
The outer planets are much larger than the terrestrial planets, composed mainly of hydrogen, helium and ices, and have lower average densities.
21.The asteroid belt, containing most of the solar system's asteroids, is located:
Answer: B
The main asteroid belt lies in the region between the orbits of Mars and Jupiter.
22.Comets are best described as:
Answer: C
Comets are often described as "dirty snowballs"—small icy bodies containing dust and frozen gases that develop glowing comas and tails when near the Sun.
23.As a comet approaches the Sun, its tail always points:
Answer: A
Solar wind and radiation pressure push the vaporized gas and dust away from the comet's nucleus, so the tail always points away from the Sun regardless of the comet's direction of travel.
24.A meteoroid that survives its passage through Earth's atmosphere and lands on the surface is called a:
Answer: A
A meteoroid burning in the atmosphere produces a visible streak called a meteor; if a fragment reaches the ground, it is called a meteorite.
25.The bright streak of light seen in the sky when a small space rock burns up in Earth's atmosphere is called a:
Answer: C
The visible flash of light caused by a meteoroid burning up due to friction with the atmosphere is called a meteor, commonly known as a shooting star.
26.A constellation is best defined as:
Answer: C
A constellation is a recognizable grouping of stars, as observed in the sky from Earth, historically named after animals, objects, or mythological characters.
27.Which of the following is a well-known constellation visible in the night sky?
Answer: D
Orion ("the Hunter") is one of the most recognizable and widely known constellations, easily identified by its distinctive belt of three stars.
28.In the celestial coordinate system, the coordinate that corresponds to longitude on Earth is called:
Answer: A
Right ascension is measured eastward along the celestial equator and serves the same purpose as longitude does on Earth's surface.
29.In the celestial coordinate system, the coordinate that corresponds to latitude on Earth is called:
Answer: B
Declination is measured as the angular distance north or south of the celestial equator, analogous to latitude on Earth.
30.Which planet is closest to the Sun?
Answer: D
Mercury is the innermost planet of the solar system, orbiting closest to the Sun.
31.The Sun is a star located approximately at the center of our solar system.
Answer: True
The Sun contains most of the solar system's mass and all the planets orbit around it, so it lies at the center of the solar system.
32.A solar eclipse occurs when the Earth passes directly between the Sun and the Moon.
Answer: False
That description is a lunar eclipse; a solar eclipse occurs when the Moon passes between the Sun and the Earth.
33.The outer planets (Jupiter, Saturn, Uranus, Neptune) are also called terrestrial planets.
Answer: False
The outer planets are called Jovian or gas giant planets; terrestrial planets refers to the small, rocky inner planets.
34.The main asteroid belt is located between the orbits of Mars and Jupiter.
Answer: True
Most asteroids in the solar system orbit the Sun within this belt between Mars and Jupiter.
35.Jupiter is the largest planet in the solar system.
Answer: True
Jupiter has by far the greatest mass and volume of any planet in the solar system.
36.The distance that light travels through a vacuum in one year is called a ______.
Answer: light year
This unit (~9.46 × 10¹² km) is used to express the vast distances between stars and galaxies.
37.A meteoroid that survives its passage through Earth's atmosphere and reaches the ground is called a ______.
Answer: meteorite
Most meteoroids burn up completely as meteors; only a fraction survive to become meteorites.
38.A recognizable pattern of stars as seen from Earth, often given a traditional name, is called a ______.
Answer: constellation
Constellations have been used historically for navigation and storytelling, such as Orion and Ursa Major.
39.The widely accepted scientific theory that the solar system formed from a collapsing cloud of gas and dust is called the ______ hypothesis.
Answer: nebular (solar nebula)
This theory explains the formation of the Sun and planets from the same rotating cloud of material.
40.On the celestial coordinate system, the coordinate analogous to latitude on Earth is called ______.
Answer: declination
Declination measures how far north or south a celestial object is from the celestial equator.