🪞 Light & Mirrors
Light bounces off a mirror by a beautifully simple rule: the angle it hits at equals the angle it leaves at. Drag the incoming beam and watch the reflection obey. Angle of incidence = angle of reflection — measured from the dotted "normal" line.
Drag the yellow handle to change where the light comes from.
The normal is an imaginary line straight out from the mirror (90° to it). We always measure light angles from the normal, not the mirror surface. This law is why periscopes, kaleidoscopes, and your bathroom mirror all work.