If the focal length of a camera lens is 20cm, the distanc...
If the focal length of a camera lens is 20cm, the distance from the film at which the lens must be set to produce a sharp image of an object 100cm away is
17cm
20cm
25cm
100cm
Correct answer is C
F = uvu+v
20 = 100×v100+v
v = 25cm