〰️ Young's Double-Slit

📖 The Physics

When light passes through two narrow slits, the two emerging waves overlap and interfere. Where crest meets crest you get a brightfringe (constructive); where a crest meets a trough it is dark(destructive).

Those neat, evenly spaced bright and dark bands could never come from tiny particles — this was Young's classic proof that light behaves as a wave.

A longer wavelength (towards red) or a bigger screen distance widens the fringes; bringing the slits closer together (smaller d) spreads them out too.