Question

A bulb is kept burning just right above the ball. Name the shape of the shadows obtained.
A) Ball
B) Hemisphere
C) Ellipse
D) Circle

Answer 1

Hint: The bulb is kept burning just right above the solid. The light can’t pass through the solid. So the light passes and makes the shadow. Hence, we are going to sketch the shadows of the given solid.

Complete step-by-step answer:
Firstly, a 3D object does cast a 3D shadow, it's just that you can usually only see two of the dimensions, where it strikes another surface. However, the shadow (defined as a dark area or shape produced by a body coming between rays of light and a surface) extends from the illuminated object to the point where it strikes another surface. This area is part of the shadow, even though it usually can't be seen, forming a third dimension (depth).

The shadow will be a two dimensional figure. Since the ball is an example of a three-dimensional shape sphere its shadow is just the compression of the sphere to its two-dimensional shape circle.
Since the bulb is just above the ball the shadow formed will be circular, as the ball cuts off the light in a circular fashion.
Hence the shadow of the ball made by the light is a circle.

So, option (D) is the correct answer.

Note: The straight lines which are passing by the sides of the object are responsible to make the shadow. You can view the cross section of a solid using shadow which requires a source of light for example, a torch or sun or bulb etc. You can view solids as cuboid, cone or sphere etc by keeping them in front of a screen and bringing the torch in front of the solid on the opposite side of the screen. You can view the shadow of the object on the screen. The size of the shadow depends on the angle and distance of the light source and the screen from each other and the object.