CBSE Class 10 Physics Light Reflection and Refraction MCQs Set H

Question: Which of the following mirrors is used by a dentist to examine a small cavity?
a) Convex mirror
b) Plane mirror
c) Concave mirror
d) Combination of convex and concave mirror
Answer: c

Question: Two thin lenses of focal lengths f₁ and f₂ are placed in contact with each other such that the combination behaves as a glass slab. Then how are f₁ and f₂ related?
a) f₁ = 1/f₂
b) f₂ = –f₁
c) f₁ = f₂
d) f₁ = √f₂
Answer: b

Question: A diver in a swimming pool wants to send a signal to a person lying on the edge of the pool by flashing his waterproof torch. He must direct the beam:
a) Vertically upwards
b) Horizontally
c) At an angle to the vertical slightly less than the critical angle
d) At an angle to the vertical slightly greater than the critical angle
Answer: c

Question: A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale. When the mirror is rotated through a small angle θ, the spot of light moves a distance y on the scale. The angle θ is given by
a) y/x
b) x/2y
c) x/y
d) y/2x
Answer: d

Question: The image which is formed behind the mirror is a
a) Real image
b) Virtual image
c) Blue image
d) Partial image
Answer: b

Question: Consider four mediums P, Q, R and S whose refractive indices are 2.14, 1.99, 2.98, and 2.16 respectively. The rate of change will be utmost when light travels from
a) P to Q
b) Q to R
c) R to S
d) S to P
Answer: b

Question: A glass beaker is filled with water up to 5 cm and placed on a 2 cm thick glass slab. When a coin at the bottom is viewed normally, its apparent depth from the water surface is approximately:
a) 2.5 cm
b) 5.1 cm
c) 3.7 cm
d) 6.0 cm
Answer: b

Question: A mirror is placed at an angle of 30° with respect to Y-axis. A light ray travelling in the negative y-direction strikes the mirror. The direction of the reflected ray is given by
a) î
b) î − √3ĵ
c) √3î − ĵ
d) î − 2ĵ
Answer: c

Question: An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced 20 cm towards the mirror, the image displacement will be
a) 30 cm away from the mirror
b) 36 cm away from the mirror
c) 36 cm towards the mirror
d) 30 cm towards the mirror
Answer: b

Question: Which of the following can make a parallel beam of light when light from a point source is incident on it?
a) Concave mirror as well as convex lens
b) Convex mirror as well as concave lens
c) Two plane mirrors placed at 90° to each other
d) Concave mirror as well as concave lens
Answer: a

Question: What is not a characteristic of a rear-view mirror in a car?
a) Convex in nature
b) Concave in nature
c) Has wider field of coverage
d) Gives a virtual image
Answer: b

Question: A student determines the focal length of a device ‘X’ by focusing the image of a distant object on a screen placed 20 cm from the device on the same side as the object. The device ‘X’ is:
a) Concave lens of focal length 10 cm
b) Convex lens of focal length 20 cm
c) Concave mirror of focal length 10 cm
d) Concave mirror of focal length 20 cm
Answer: d

Question: A student has focussed on the screen of a distant building using a convex lens. If the building is blue, the image formed on the screen will be:
a) Virtual, erect, diminished and green shade
b) Real, inverted, diminished and in violet shade
c) Real, inverted, diminished and in blue shade
d) Virtual, inverted, diminished and in blue shade
Answer: c

Question: The image obtained is always erect in
a) Convex mirror
b) Concave mirror
c) Plane mirror
d) Both a and c
Answer: d

Question: Magnification produced by a rear-view mirror fitted in vehicles
a) Is less than one
b) Is more than one
c) Is equal to one
d) Can be more than or less than one depending upon the position of the object in front of it
Answer: a

Question: The focal length of a concave mirror is 10 cm. The radius of curvature of the mirror will be:
a) 10 cm
b) 20 cm
c) 30 cm
d) 40 cm
Answer: b

Question: A magnifying glass is a
a) Both convex and concave
b) Concave lens
c) Diverging lens
d) Convex lens
Answer: d

Question: A point object is placed at a distance of 20 cm from a convex mirror of focal length 20 cm. The image will form at:
a) At infinity
b) At focus
c) At the pole
d) Behind the mirror
Answer: d

Question: The object is placed at distance 10 cm in front of a plane mirror. The distance of image from mirror will be:
a) 5 cm
b) 10 cm
c) 20 cm
d) 0 cm
Answer: b

Question: In an experiment to trace the path of a ray of light through a triangular glass prism, a student would observe that the emergent ray
a) Is parallel to the incident ray
b) Is along the same direction of incident ray
c) Gets deviated and bends towards the thinner part of the prism
d) Gets deviated and bends towards the thicker part (base) of the prism
Answer: d

Question: When the object is placed between P and F in case of concave mirror then the image formed will be at
a) At C
b) At infinity
c) At F
d) Behind the mirror
Answer: d

Question: Where should an object be placed in front of convex lens to get a real image of the size of the object?
a) At the principal focus of the lens
b) At twice the focal length
c) At infinity
d) Between the optical centre of the lens and its principal focus
Answer: b

In the following question, a statement of Assertion
(A) is followed by a statement of Reason (R). Answer: these questions by selecting appropriate option given below:
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A)
(c) Assertion (A) is true but Reason (R) is false.
(d) Assertion (A) is false but Reason (R) is true.

Question:
Assertion (A): A convex mirror is used as a driver’s mirror.
Reason (R): Because convex mirror’s field of view is large and images formed are virtual, erect and diminished.
Answer: a

Question:
Assertion (A): For observing traffic at back, the driver mirror is convex mirror.
Reason (R): A convex mirror has much large field of view than a plane mirror.
Answer: c

Question:
Assertion (A): Propagation of light through an optical fiber is due to total internal reflection taking place at the core-clade interface.
Reason (R): Refractive index of the material of the core of the optical fiber is greater than of air.
Answer: b

Question:
Assertion (A): If the rays are diverging after emerging from a lens; the lens must be concave.
Reason (R): The convex lens can give diverging rays.
Answer: d

Question:
Assertion (A): It is not possible to see a virtual image by eye.
Reason (R): The rays that seem to emanate from a virtual image do not in fact emanates from the image.
Answer: d

Question:
Assertion (A): A virtual image cannot be photographed.
Reason (R): Only real objects are photographed.
Answer: c

Question:
Assertion (A): Higher is the refractive index of a medium or denser the medium, lesser if the velocity of light in that medium.
Reason (R): Refractive index is inversely proportional to velocity.
Answer: a

Question:
Assertion (A): The height of an object is always considered positive.
Reason (R): An object is always placed above the principal axis in the upward direction.
Answer: a

Question:
Assertion (A): Large concave mirrors are used to concentrate sunlight to produce heat in solar cookers.
Reason (R): Concave mirror converges the light rays falling on it to a point.
Answer: a

Question:
Assertion (A): The image formed by a concave mirror is certainly real if the object is virtual.
Reason: The image formed by a concave mirror is certainly virtual if the object is real.
Answer: c

(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If Assertion is incorrect but Reason is correct.

Question:
Assertion : The image of a point object situated at the centre of hemispherical lens is also at the centre.
Reason : For hemisphere Snell’s law is not valid.
Answer: c

Question:
Assertion : Light rays retrace their path when their direction is reversed (Law of reversibility of light rays)
Reason : For the refraction of light, water is denser than air, but for the refraction of sound, water is rarer than air.
Answer: c

Question:
Assertion : The mirrors used in search lights are parabolic and not concave spherical.
Reason : Silvered plano convex lens is used in search light.
Answer: c

Question:
Assertion : When a concave mirror is held under water, its focal length will increase.
Reason : The focal length of a concave mirror is independent of the medium in which it is placed.
Answer: d

Question:
Assertion : If a spherical mirror is dipped in water, its focal length remains unchanged.
Reason : A laser light is focused by a converging lens. There will be a significant chromatic aberration.
Answer: c

True / False :

Question: Light travels faster in glass than in air.
Answer: False

Question: The image in a plane mirror lies as far behind the mirror.
Answer: True

Question: Image formed by a plane mirror is always virtual and erect.
Answer: True

Question: Light travels in vacuum with an enormous speed of 3 × 108 ms–1.
Answer: True

Question: A ray of light passing through the optical centre of a lens will emerge without any deviation.
Answer: True

Question: The speed of light is different in different media.
Answer: True

Question: When a ray of light travels from air to water, its speeds up.
Answer: False

Question: The incident ray, the normal to the mirror at the point of incidence and the reflected ray, all lie in the same plane.
Answer: True

Question: A lens that is thicker at the middle than at the edges is a diverging lens.
Answer: False

Question: The principal focus of a spherical mirror lies midway between the pole and centre of curvature.
Answer: True