Question

Light cannot reach behind an object because it cannot

Answer 1

Answer: i think you meant why it cannot ... well , if you did , here is your answer :)

Explanation:

Light consists of waves. The bending of waves around an obstacle, when they meet an obstacle, is called diffraction. For diffraction to occur the size of the obstacle must be of the same order of magnitude as the  wave length of the wave ...

HOPE THIS HELPED :)