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Question:
A biconvex lens of focal length f forms a circular image of
radius r of sun in focal plane. Then which option is correct ?
A biconvex lens of focal length f forms a circular image of
radius r of sun in focal plane. Then which option is correct ?
Updated On: May 24, 2022
- $\pi r^2 \propto f$
- $\pi r^2 \propto f^2$
- If lower half part is convered by black sheet, then area of the image is equal to $\pi r^2/2$
- If f is doubled, intensity will increase
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The Correct Option is B
Solution and Explanation
$\hspace25mm r=f \, tan \, \theta$
or $\hspace25mm r ? f \, \therefore \, \, \, \, \pi r^2 ? f^2$
or $\hspace25mm r ? f \, \therefore \, \, \, \, \pi r^2 ? f^2$
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