The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall `3 m` away by means of a large convex lens. What is the maximum possible focal length of the lens required for the purpose ?

Options

A. 3.25 m
B. 1.55 m
C. 0.75 m
D. 0.28 cm

Answer

C

Explanation

For a real image on screen formed by curve lens, the minimum distance between object plane and screen, should be four times the focal lens.
`4f_(max) = 3 rArr f_(max) = (3)/(4) = 0.75` m.