Rays of light from Sun falls on a biconvex lens of focal length and the circular…

PHYSICS · Single correct · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction

Problem

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 (1) Area of image is

\pi r^2

and area is directly proportional of

f

(2) Area of image is

\pi r^2

and area is directly proportional to

f^2

(3) Intensity of image increases if

f

is increased (4) If lower half of the lens is covered with black paper area will become half