Why does light reflect in a mirror?

Answer 1

A glass mirror is a piece of glass with a reflective coating on the back side. If a surface is extremely smooth and flat, it will reflect light waves without distorting them. Metal mirrors are less efficient, generally because the metal is difficult to polish to the same smoothness as glass. Water can be an effective mirror, if the surface of it is perfectly smooth.

The question is Why? The answer is that light reflects off everything. It is normal for light to reflect. A photon hits an atom or molecule of substance and it bounces off it. That's how come we can see things. Because light bounces off them. So it is no mystery that light bounces off (reflects) mirrors.

The only difference between mirrors and other things is they bounce nearly ALL the light wave lengths back and are smooth to not distort the reflection and we are accustomed to use them for looking at ourselves and come to think of them as different.

If all the wavelengths were not reflected the mirror would have a colour. The colour of the reflected wavelengths of light. Absorption of a wavelength would be, I'd guess (I'm no scientist) the losing of some of the energy of those photons - lose all its energy and it'd be extinguished, I guess.

Possibly the question really should be Why Can't We See A Mirror? because that's the funny thing: we see only the reflections and fail to see the reflective surface and that's because, again, 'seeing' means looking at reflected light.

light bounces off the reflecting surface of the mirror. Note the reflecting surface of a mirror is commonly the metallic coating on the back of a sheet of glass.

So if it's reflecting off metal why not make metal mirrors with no glass? Because this way is cheaper and easier. Depositing a fine layer of metal on a totally smooth piece of glass is a lot easier than taking a piece of metal and and polishing to a high finish - and then keep it that way.