An image of the sun is formed by a lens of the focal length of on the metal surface of a photoelectric cell and a photoelectric current is produced. The lens forming the image is then replaced by another of the same diameter but of focal length . The photoelectric current in this case is
Step 1: Given:
The focal length of the first lens =
The focal length of the second lens =
Current produced =
Diameter of the second lens = diameter of the first lens.
Step 2: Finding the amount of current in the case of using the second lens:
Hence, the answer is (C)