ELI5 If you look at a dark phone screen you can choose whether you see what’s happening on the screen or you can use the screen as a mirror. How does that work?

Question

ELI5 If you look at a dark phone screen you can choose whether you see what’s happening on the screen or you can use the screen as a mirror. How does that work?

In: Biology

Answer 1

Focus. You’re either focusing your eyes on the screen itself and the light emitted from the screen, or you’re focusing on a separate light source, i.e., the reflection.