Question

A camera fitted with a lens of focal length 50 mm is being used to photograph a flower that is 5 cm in diameter. The flower is placed 20 cm in front of the camera lens.

(a) At what distance from the film should the lens be adjusted to obtain a sharp image of the flower ? 

(b) What would be the diameter of the image of the flower on the film ?

(c) What is the nature of camera lens ?

Answer 1

(a) u = -20 cm = -200 mm

f = 50 mm

v = 66.6 mm = 6.66 cm

The films should be at a distance of 6.66 cm behind the camera lens.

(b) d₁ = 5 cm = 50 mm

d₂ = 16.65 mm = 1.66 cm

(c) It is a convex lens.