NCERT Solutions for Class 7th Science Chapter 11 Light according to the Latest Syllabus Of JKBOSE and CBSE NCERT Books
1. Fill in the blanks:
(a) An image that cannot be obtained on a screen is called virtual.
(b) Image formed by a convex mirror is always virtual and smaller in size.
(c) An image formed by a plane mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a real image.
(e) An image formed by a concave lens cannot be obtained on a screen.
2. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) We can obtain an enlarged and erect image by a convex mirror. (F)
(b) A concave lens always forms a virtual image. (T)
(c) We can obtain a real, enlarged, and inverted image by a concave mirror. (T)
(d) A real image cannot be obtained on a screen. (F)
(e) A concave mirror always forms a real image. (F)
3. Match the items given in Column I with one or more items of Column II:
(a) Plane mirror – (v) The image is erect and of the same size as the object.
(b) Convex mirror – (vi) The image is erect and smaller in size than the object. (ii) Can form image of objects spread over a large area.
(c) Convex lens – (i) Used as a magnifying glass.
(d) Concave mirror – (iii) Used by dentists to see enlarged image of teeth. (iv) The image is always inverted and magnified.
(e) Concave lens – (ii) Can form image of objects spread over a large area.
4. State the characteristics of the image formed by a plane mirror?
A plane mirror forms an image that is virtual, erect, and of the same size as the object. The image is laterally inverted, meaning the left side of the object appears on the right side of the image and vice versa.
5. Find out the letters of the English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself.
The letters A, H, I, M, O, T, U, V, W, X, and Y appear exactly like their images in a plane mirror.
6. What is a virtual image? Give one situation where a virtual image is formed?
A virtual image is formed when the light rays appear to diverge from a point, but do not actually meet. A virtual image cannot be obtained on a screen. One situation where a virtual image is formed is when looking at oneself in a plane mirror.
7. State two differences between a convex and a concave lens?
A convex lens converges light rays and can form real or virtual images. It is thicker in the middle than at the edges. A concave lens diverges light rays and always forms virtual images. It is thinner in the middle than at the edges.
8. Give one use each of a concave and a convex mirror?
A concave mirror is used by dentists to see an enlarged image of teeth. A convex mirror is used as a rearview mirror in vehicles to provide a wider field of view.
9. Which type of mirror can form a real image?
A concave mirror can form a real image.
10. Which type of lens always forms a virtual image?
A concave lens always forms a virtual image.
11. A virtual image larger than the object can be produced by a:
(i) Concave lens
(ii) Concave mirror
(iii) Convex mirror
(iv) Plane mirror
Answer: (ii) Concave mirror
12. David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be:
(i) 3 m
(ii) 5 m
(iii) 6 m
(iv) 8 m
Answer: (ii) 5 m
13. The rearview mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rearview mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be:
(i) 1 m/s
(ii) 2 m/s
(iii) 4 m/s
(iv) 8 m/s
Answer: (iii) 4 m/s
