Question

A student had a ball, a screen, and a torch in a 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.​

Answer 1

The shadow formed depends on the placement of the light source and the screen.
The conditions when a shadow is not obtained on the screen are:

$1$. When the light rays from the torch are parallel to the screen rather than falling on it
$2$. When the source of light is at a great distance from the object

If both these problems are fixed, a shadow will form.
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