Question

As the light ray travels from a rarer medium (air) to a denser medium (mirror). Why does the mirror reflect light?

Answer 1

Refraction:

1. Refraction is the phenomenon that takes place due to the bending of light when it travels from medium to another.
2. A light ray refracts whenever it travels at an angle into a medium of a different refractive index. This change in speed results in a change in direction. As an example, consider light traveling from air into glass. The speed of light decreases as it continues to travel at a different angle.

Explanation:

1. Silver is a good reflector of light and mirrors are usually coated with a silver coating so that they reflect all the light that falls on them.
2. The silver atoms behind the glass absorb the photons of incoming light energy and become excited. But that makes them unstable, so they try to become stable again by getting rid of the extra energy and they do that by giving off some photons.
3. The back of a mirror is usually covered with some sort of darkly colored, protective material to stop the silver coating from getting scratched, and also to reduce the risk of any light seeping through from behind.
4. Silver reflects light better than almost anything else because it gives off almost as many photons of light falling on it. The photons that come out of the mirror are pretty much the same as the ones that go into it.

Hence, the mirror reflects light that falls on it because of the silver coating that is present on the back side of the mirror.