Ans. Mirrors reflect because of the presence of free electrons, which makes mirrors electrically conductive. The silver atoms behind the glass absorb the photons of incoming light energy and become excited. However, 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 more photons. Silver reflects light better than anything else. It gives off as many photons as the amount falling on it. The photons that come out of the mirror are almost the same as the ones that go into it.