A convex lens of focal length $40 \mathrm{~cm}$ forms an image of an extended source of light on a photoelectric cell. A current I is produced. The lens is replaced by another convex lens having the same diameter but focal length $20 \mathrm{~cm}$. The photoelectric current now is :
Solution
<p>As amount of energy incident on cell is same so current will remain same.</p>
About this question
Subject: Physics · Chapter: Optics · Topic: Lenses and Optical Instruments
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