An image of the sun is formed by a lens of 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 and image of sun is again formed on the same metal plate. The photoelectric current in this case is

Question

An image of the sun is formed by a lens of 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 and image of sun is again formed on the same metal plate. The photoelectric current in this case is

Infinity Learn · Accepted Answer

Since aperture is same in both cases, same no. of photons pass through lens producing same photo current.

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