question_answer

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) area of image is \[\pi {{r}^{2}}\] and area is directly proportional of

B) area of image is \[\pi {{r}^{2}}\] and area is directly proportional to \[{{f}^{2}}\]

C) intensity of image increases if f is increased

D) if lower half of the lens is covered with black paper area will become half