Light NCERT Exercise Solution
Question 1: Fill in the blanks:
- An image that cannot be obtained on a screen is called ____________.
- Image formed by a convex __________ is always virtual and smaller in size.
- An image formed by a __________ mirror is always of the same size as that of the object.
- An image which can be obtained on a screen is called a _________ image.
- An image formed by a concave ___________ cannot be obtained on a screen.
Answer: (a) virtual, (b) mirror, (c) plane, (d) real, (e) lens
Question: 2 -Mark âTâ if the statement is true and âFâ if it is false:
- We can obtain an enlarged and erect image by a convex mirror.
- A concave lens always forms a virtual image.
- We can obtain a real, enlarged and inverted image by a concave mirror.
- A real image cannot be obtained on a screen.
- A concave mirror always form a real image.
Answer: (a) F, (b) T, (c) F, (d) F, (e) F
Question 3: Match the items given in Column I with one or more items of Column II.
| Column I | Column II |
|---|---|
| (1) A plane mirror | (a) Used as a magnifying glass |
| (2) A convex mirror | (b) Can form image of objects spread over a large area |
| (3) A convex lens | (c) Used by dentists to see enlarged image of teeth |
| (4) A concave mirror | (d) The image is always inverted and magnified |
| (5) A concave lens | (e) The image is erect and of the same size as the object |
| (f) The image is erect and smaller in size than the object |
Answer: (1) e, (2) b, (3) a, (4) c, (5) f
Question 4: State the characteristics of the image formed by a plane mirror.
Answer: In case of plane mirror, the image is erect, virtual and of same size as the object.
Question 5: Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.
Answer: Some examples: A, H, I, M, O, T, U, V, W and X
Question: 6: What is a virtual image? Give one situation where a virtual image is formed.
Answer: The image which cannot be obtained on a screen is called virtual image. For example, virtual image is always formed in case of plane mirror and convex mirror.
Question 7: State two differences between a convex and a concave lens.
Answer: A convex lens can make enlarged image, while a concave lens would always make smaller image. A convex lens usually makes real image, while a concave lens always makes a virtual image.