Class 7 Science


NCERT Solution Part 2

Question 8: Give one use each of a concave and a convex mirror.

Answer: (a) Concave mirror is used in solar furnace.
(b) Convex mirror is used in rear view mirrors.

Question 9: Which type of mirror can form a real image?

Answer: Concave mirror

Question 10: Which type of lens forms always a virtual image?

Answer: Concave lens

Choose the correct option in questions 11–13

Question 11: A virtual image larger than the object can be produced by a

  • Concave lens
  • Concave mirror
  • Convex mirror
  • Plane mirror

Answer: (c) Concave mirror

Question 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

  • 3 m
  • 5 m
  • 6 m
  • 8 m

Answer: (a) 3 m

Question 13: The rear view 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 rear view 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

  • 1 m/s
  • 2 m/s
  • 4 m/s
  • 8 m/s

Answer: (b) 2 m/s