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
The correct answer is: C
Explanation
F = \(\frac{uv}{u + v}\)20 = \(\frac{100 \times v}{100 + v}\)
v = 25cm