Class 10 Science Chapter 9 Assertion and Reason Questions - Light Reflection and Refraction

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Question 1:

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.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (b) 

Solution: Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A). The assertion correctly describes the law of reversibility of light rays, while the reason correctly describes the behavior of sound and light refraction, but it is unrelated to the assertion.

Question 2:

Assertion: It is not possible to see a virtual image by eye. Reason: The rays that seem to emanate from a virtual image do not in fact emanate from the image.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (d) 

Solution: Assertion (A) is false but reason (R) is true. A virtual image can be seen by the eye; the rays appear to come from the image, although they do not actually emanate from it.

Question 3:

Assertion: Plane mirrors may form a real image. Reason: Plane mirrors form virtual images if the object is real.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (d) 

Solution: Assertion (A) is false but reason (R) is true. Plane mirrors always form virtual images for real objects, not real images.

Question 4:

Assertion: An object is placed at a distance of $ff$f from a convex mirror of focal length $ff$f, its image will form at infinity. Reason: The distance of the image in a convex mirror can never be infinity.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (d) 

Solution: Assertion (A) is false but reason (R) is true. The image formed by a convex mirror is always virtual and at a finite distance from the mirror.

Question 5:

Assertion: The mirror used in searchlights is concave spherical. Reason: In a concave spherical mirror, the image formed is always virtual.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (c) 

Solution: Assertion (A) is true but reason (R) is false. Concave mirrors are used in searchlights because they can focus light into a parallel beam. However, concave mirrors can form both real and virtual images.

Question 6:

Assertion: Concave mirrors are used as make-up mirrors. Reason: When the face is held within the focus of a concave mirror, a diminished image of the face is seen in the concave mirror.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (c) 

Solution: Assertion (A) is true but reason (R) is false. Concave mirrors are used as make-up mirrors because they can produce a magnified image of the face when it is placed within the focal length of the mirror.

Question 7:

Assertion: Propagation of light through an optical fiber is due to total internal reflection taking place at the core-cladding interface. Reason: The refractive index of the material of the core of the optical fiber is greater than that of air.

Options: (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. (e) Both assertion (A) and reason (R) are false.

Correct Answer: Option (b) 

Solution: Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A). The propagation of light in optical fibers is due to total internal reflection, but this occurs at the core-cladding interface, not because of the refractive index difference between the core and air. The cladding has a lower refractive index than the core, which is essential for total internal reflection to occur.