Find the photoelectric current in the given scenario

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 1 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

  1. 2l
  2. 4l
  3. 1
  4. 1/2

Answer: Option 3
Explanation: As the diameter on lens remain same, both the lens will collect the same amount of light. Therefore, the intensity of the light will remain the same as a result the photoeletric current will also remain the same.

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