An image of the sun is formed by a lens, of the focal length of 30 cm, on the metal surface of a photoelectric cell and a photoelectric current I is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case is

Options

A. `I//2`
B. `2I`
C. `I`
D. `4 I`

Answer

C

Explanation

The current `I` is proportional to light energy falling on the lens per second with is same in the two cases. Hence same `I`.