Ray Optics

JEE Main level, single correct, medium

165 of 295

Question 165 of 295

A convex lens of focal length 40cm40cm forms an image of an extended source of light on a photoelectric cell. A current II is produced. The lens is replaced by another convex lens having the same diameter but focal length 20cm20cm. The photoelectric current now is

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Answer: (D) II

For a light of any given frequency, the photoelectric current is directly proportional to the intensity of light.
As the diameter of the lens remains the same, both lenses will collect the same amount of light. Therefore, the intensity of the light will remain the same.
Hence, this is the correct option.

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