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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Lenses that are made by combining two spherical transparent surfaces are called spherical lenses. In general, there are two kinds of spherical lenses. Lenses that are made by joining two spherical surfaces that bulge outward are convex lenses, whereas lenses that are made by joining two spherical surfaces that curve inward are concave lenses.
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