CBSE Class 8 Science Chapter 10: Light: Mirrors and Lenses — Assertion & Reason
CBSE Class 8 Science Assertion & Reason
Expert crafted · Instant PDF download · 2026-27
The following Assertion and Reason questions are based on Chapter 10: Light: Mirrors and Lenses from the NCERT Class 8 Science textbook Curiosity. Each question has four options — read both the Assertion (A) and Reason (R) carefully before selecting your answer.
How to attempt Assertion & Reason questions:
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion & Reason Questions
1
Assertion (A): A spherical mirror is created by slicing a hollow glass sphere and using the cut piece.
Reason (R): The shape of a spherical mirror is such that it can be thought of as a part of an imaginary hollow sphere.
Reason (R): The shape of a spherical mirror is such that it can be thought of as a part of an imaginary hollow sphere.
Answer: (d)
A is false, but R is true. Spherical mirrors are not actually made by slicing a hollow glass sphere. Instead, they are created by grinding and polishing a flat glass piece into a curved surface.
2
Assertion (A): A spherical mirror with a reflecting surface that curves inwards is called a concave mirror.
Reason (R): The outer curved surface of a shiny metallic spoon acts like a concave mirror.
Reason (R): The outer curved surface of a shiny metallic spoon acts like a concave mirror.
Answer: (c)
A is true, but R is false. The outer curved surface of a spoon bulges outwards, so it acts like a convex mirror. The inner curved surface acts like a concave mirror.
3
Assertion (A): When an object is placed very close to a concave mirror, the image formed is erect and enlarged.
Reason (R): As the object is moved farther away from a concave mirror, the image becomes inverted.
Reason (R): As the object is moved farther away from a concave mirror, the image becomes inverted.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements correctly describe the properties of images formed by a concave mirror at different distances, but one does not explain the reason for the other.
4
Assertion (A): Convex mirrors are preferred for use as side-view mirrors in vehicles.
Reason (R): Convex mirrors always form an erect and diminished image, providing a much wider view of the traffic behind.
Reason (R): Convex mirrors always form an erect and diminished image, providing a much wider view of the traffic behind.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Because a convex mirror curves outwards, it shrinks the image size, allowing the driver to see a much larger area of the road behind them.
5
Assertion (A): Dentists use concave mirrors to inspect patients' teeth.
Reason (R): A concave mirror provides an enlarged view of the teeth when held close to them inside the mouth.
Reason (R): A concave mirror provides an enlarged view of the teeth when held close to them inside the mouth.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Since concave mirrors produce enlarged, erect images when objects are held close, they are perfect for giving dentists a clear, magnified view of a tooth.
6
Assertion (A): When a light ray falls along the normal on a plane mirror, the angle of reflection is 90°.
Reason (R): The angle of incidence is always equal to the angle of reflection according to the laws of reflection.
Reason (R): The angle of incidence is always equal to the angle of reflection according to the laws of reflection.
Answer: (d)
A is false, but R is true. When a light ray falls along the normal, the angle of incidence is 0° (since it is measured from the normal). Therefore, the angle of reflection is also 0°, not 90°.
7
Assertion (A): If a paper carrying a reflected beam is bent at the edge of a table, the reflected beam disappears from the bent portion.
Reason (R): The incident ray, the normal at the point of incidence, and the reflected ray all lie in the same plane.
Reason (R): The incident ray, the normal at the point of incidence, and the reflected ray all lie in the same plane.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Bending the paper creates a new plane. Because the laws of reflection state all three must lie in the same plane, the reflected ray cannot travel along the newly bent plane.
8
Assertion (A): The laws of reflection are valid for plane mirrors but do not apply to spherical curved mirrors.
Reason (R): Spherical mirrors cause parallel beams of light to either converge or diverge instead of remaining parallel.
Reason (R): Spherical mirrors cause parallel beams of light to either converge or diverge instead of remaining parallel.
Answer: (d)
A is false, but R is true. The laws of reflection are valid for ALL kinds of mirrors, including plane, concave, and convex. While the curved surface causes the overall beam to converge or diverge, each individual ray still perfectly obeys the laws of reflection.
9
Assertion (A): A concave mirror can be used to burn a piece of paper using sunlight.
Reason (R): A concave mirror converges multiple parallel rays of sunlight to a single point, producing concentrated heat.
Reason (R): A concave mirror converges multiple parallel rays of sunlight to a single point, producing concentrated heat.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Concave mirrors are converging mirrors, so they focus the sun's light and heat energy onto a sharp bright spot, which is strong enough to ignite paper.
10
Assertion (A): A lens is a piece of transparent material, like glass or plastic, which has curved surfaces.
Reason (R): Unlike mirrors, lenses allow light to pass through them rather than reflecting it back.
Reason (R): Unlike mirrors, lenses allow light to pass through them rather than reflecting it back.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements are correct definitions and properties of a lens, but allowing light to pass through does not explain why it has curved surfaces.
11
Assertion (A): A convex lens is thicker at the edges as compared to the middle.
Reason (R): A convex lens is also known as a converging lens because it converges the light beams passing through it.
Reason (R): A convex lens is also known as a converging lens because it converges the light beams passing through it.
Answer: (d)
A is false, but R is true. A convex lens is thicker in the middle and thinner at the edges. A concave lens is the one that is thicker at the edges.
12
Assertion (A): A magnifying glass uses a concave lens to make small letters appear bigger.
Reason (R): When an object is placed close to a convex lens, the object appears erect and enlarged in size.
Reason (R): When an object is placed close to a convex lens, the object appears erect and enlarged in size.
Answer: (d)
A is false, but R is true. A magnifying glass uses a convex lens, not a concave lens, precisely because a convex lens produces an enlarged image when held close to an object.
13
Assertion (A): An object seen through a concave lens always appears erect and diminished in size.
Reason (R): A concave lens diverges multiple parallel beams of light passing through it.
Reason (R): A concave lens diverges multiple parallel beams of light passing through it.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. Both statements are true characteristics of a concave lens, but the diverging nature of the light rays is not the direct explanation given for the diminished image size in this context.
14
Assertion (A): A small drop of water placed over printed text can make the letters appear enlarged.
Reason (R): The curved outer surface of the water drop acts like a simple convex lens.
Reason (R): The curved outer surface of the water drop acts like a simple convex lens.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Because the water drop forms a shape that is thicker in the middle (curved outwards), it behaves exactly like a convex magnifying glass, enlarging the text below it.
15
Assertion (A): Solar concentrators use large plane mirrors to melt steel in solar furnaces.
Reason (R): Devices which concentrate sunlight into a small area to generate immense heat are called solar concentrators.
Reason (R): Devices which concentrate sunlight into a small area to generate immense heat are called solar concentrators.
Answer: (d)
A is false, but R is true. Solar concentrators use curved mirrors (concave) or lenses to focus sunlight into a single point to generate that immense heat; plane mirrors cannot focus light in this way.
❓ Frequently Asked Questions
What is covered in CBSE Class 8 Science Chapter 10 Light: Mirrors and Lenses?
This chapter covers all key topics from Light: Mirrors and Lenses as per CBSE 2026-27 syllabus.
Is this Assertion & Reason useful for CBSE board exams?
Yes, designed for CBSE Class 8 board exam preparation covering the complete syllabus.
Are these CBSE Class 8 Science Assertion & Reason updated for 2026-27?
Yes, all content at eBookPublisher is updated as per the latest 2026-27 CBSE syllabus.
How many chapters are in CBSE Class 8 Science?
All chapters of CBSE Class 8 Science are covered at eBookPublisher with free Assertion & Reason for each chapter.
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