Question

A ray of light is travelling an angle 20 degree with x-axis at what angle with x-axis must a plane mirror be rotated from its initial position along x-axis so that it becomes vertically upward after reflection

Answer 1

Answer:

Let us first place the mirror horizontally. The reflected ray now goes at an angle of 20∘ above the horizontal as shown below

To make the reflected ray vertical, it has to be rotated anticlockwise by 70∘. Hence the mirror must be rotated by 70∘2=35∘

⇒ the angle of the mirror with the horizontal = 35∘. this is the answer -- six pack