Question

Upper half of a convex lens is covered with a black paper. Draw a ray diagram to show the formation of image of an object placed at a distance of 2F from such a lens. Mention the position and nature of the image formed. State the observable difference in the image obtained if the lens is uncovered. Give reason to justify your answer.

Answer 1

When the upper half of a convex lens is covered with black paper, the entire lens still contributes to the image formation, but only half the number of rays from the object pass through the lens.

Covering a part of the lens does not affect the position or nature of the image, because every part of the lens can form the complete image. However, with fewer rays, the image appears dimmer or less bright. This supports the wave theory of light and the principle of superposition.