An emergant property that describes when a [[Wave]] can no longer be treated as a [[Ray]]. In this context, a beam of some wave (lets say, [[Electromagnetic Radiation|Light]]), is converted from being a *beam* and instead as a source radiating away from the hole in the wall. >[!example] Diffraction Grating with 1 hole >![[Diffraction .excalidraw.svg|300]] >%%[[Diffraction .excalidraw.md|🖋 Edit in Excalidraw]]%% ![[Diffraction _0.excalidraw.svg]] %%[[Diffraction _0.excalidraw.md|🖋 Edit in Excalidraw]]%% $\begin{align} \sin \theta &= \frac{\ell}{d} \\ \theta &\approx \frac{\ell}{d} \\ \ell &= \theta d \\ \frac{y}{L} &\approx \frac{\ell}{d}\\ y &= L \frac{\lambda}{2d} \\ \ell &= \frac{\lambda}{2} \\ \frac{y}{L} &\approx \frac{2\lambda}{d} \end{align} $ $\huge y = L \frac{m\lambda}{2d}, m \in \Z $