Photoelectric EffectHard
Question
An image of the sun is formed by a lens of focal length 30 cm on the metal surface of a photo-electric 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 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). (Assume saturation current only).
Options
A.I/2
B.2I
C.I
D.4 I
Solution
The current I is proportional to light energy falling on the lens per second which is same in the two cases. Hence same I.
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