Question

One-half of a convex lens of focal length 20 cm is covered with a black paper. 

(i) Will the lens produce a complete image of the object?

(ii) Show the formation of image of an object placed at 2F₁ of such covered lens with the help of a ray diagram. 

(iii) How will the intensity of the image formed by half covered lens compare with non-covered lens?

Answer 1

(i) Yes, complete image will be formed.

(ii)

(iii) Intensity will be reduced as the light falling on the lower (covered) portion will not reach the position of image.