Eli5: how do mirrors reflect back if they’re just made of glass and why are some materials reflective and others not?

Question

I’ve heard that mirrors have something behind them to make the glass reflective but how does that work?

In: Engineering

Answer 1

They’re not just glass. They’re glass with a thin layer of silver or aluminum behind it. Glass alone reflects only a small fraction of light, but those metals reflect a very large portion so you get a very clear relfection if the surface is smooth enough