Question

give four characteristics of shadow

Answer 1

It is always either large or same size as that of the object. Always black in colour It's position changes depending upon the position of source of light Can be formed on any kind of screen

Answer 2

These are the characteristics I could quickly come up with, but I guess there are more.

There are strong edges on the shadow borders
The shadow is ‘darker’ than the surrounding area
The shadow usually ‘deforms’ when an object is rotated
Due to absence of the primary lighting in the shade, the color tends to be dominated mostly by the main diffuse lighting source (which is in most cases the sky --> blue)