Home
Class 12
PHYSICS
A biconvex lens of focal length f forms ...

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

` pi r^(2) prop f`

B

` pi r^(2) prop f^(2)`

C

If lower half part is covered by black sheet, then area of the image is equal to `( pi r ^(2))/( 2)`

D

If f is doubled, intensity will increase

Text Solution

Verified by Experts

The correct Answer is:
B
`tan beta = (AB)/(AC) rArr AB = AC tan beta `
`rArr 2 r = f tan beta `
Area of image `(pi r^(2)) prop f^(2)`
Promotional Banner

Similar Questions

Explore conceptually related problems

Rays of light from Sun falls on a biconvex lens of focal length f and the circular image of Sun of radius r is formed on the focal plane of the lens. Then

A convex lens of focal length f produces a virtual image n times the size of the object. Then the distance of the object from the lens is

A convex lens of focal length f will form a magnified real image of an object if the object is placed

A convex lens of focal length f forms an image which is 13/ times the size of the object. Then, the distance of object from the lends is

A concave lens of focal length f forms an image which is n times the size of the object What is the distance of the object from the lens in terms of f and n?