A student had a ball, a screen and a torch in working condition. He tried to form a shadow of the ball on the screen by placing them at different positions. Sometimes the shadow was not obtained. Explain.
Some of the reason due to which shadow was not obtained can be as follows:
(i) The screen is far away from the ball.
(ii) The torch is kept away from the ball.
(iii) The beam of light from the torch is falling parallel to the screen on the ball.