LONG ANSWER QUESTIONS

Q.1 A football match is being played at night in a stadium with flood lights ON. You can see the shadow of a football kept at the ground but cannot see its shadow when it is kicked high in the air. Explain.

Ans. When the football is kept on the ground, the floodlights illuminate it and cast a shadow on the ground. However, when the football is kicked high in the air, it moves out of the direct light source of the floodlights, resulting in the absence of a shadow. As it ascends, the angle of light and the position of the football change, causing the shadow to disappear from view.

Q.2 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.

Ans. The student may not have obtained a shadow of the ball on the screen when the torch was not positioned correctly relative to the ball and the screen. If the torch was too close to the ball or the screen, or if there were other sources of light interfering, the shadow might not have formed clearly. Proper alignment and distance between the objects and the light source are essential for shadow formation.

Q. 3 A sheet of plywood, a piece of muslin cloth and that of a transparent glass, all of the same size and shape were placed at A one by one in the arrangement shown in fig 11.12. Will the shadow be formed in each case? If yes, how will the shadow on the screen be different in each case? Give reasons for your answer.

Ans. Shadow will not be formed in any of the cases. Only the piece of muslin cloth and the sheet of plywood will cast a shadow on the screen.
(i) The piece of muslin cloth will form a lighter shadow as it allows light to pass through it partially.
(ii) The sheet of plywood will form a dark shadow as it blocks the path of light completely.
(iii) The transparent glass will allow most of the light to pass through it. So, no shadow will be obtained on the screen.