Solveeit Logo

Question

Question: A biconvex lens of focal length f forms a circular image of radius r in focal plane. Then –...

A biconvex lens of focal length f forms a circular image of radius r in focal plane. Then –

A

pr2µ f2

B

pr2µ f

C

If lower half is covered by black sheet, then area of the image is equal to

D

If f is doubled, intensity will increase

Answer

pr2µ f2

Explanation

Solution

rf=tan\frac { \mathrm { r } } { \mathrm { f } } = \tana \ r = f tan a

Area = pr2 = pf2 (tan a)2

\ pr2 µ f2