Question
Question: An image of the sun is formed by a lens of focal length 30 cm on the metal surface of a photoelectri...
An image of the sun is formed by a lens of focal length 30 cm on the metal surface of a photoelectric cell and it produces a current I. The lens forming the image is then replaced by another lens of the same diameter but of focal length of 15 cm. The photoelectric current in this case will be -
(In both cases the plate is kept at focal plane and normal to the axis lens)
A
I/2
B
2I
C
I
D
4I
Answer
I
Explanation
Solution
The number of photons incident in both the case is same.