u/notesforphysics

Ever wonder why your reflection in a calm lake looks almost perfect, but a sunlit brick wall doesn't reflect anything clearly? It comes down to two simple laws of reflection (angle of incidence = angle of reflection, and everything lying in the same plane) plus whether the surface is smooth (regular reflection) or rough (irregular reflection).

I put together a quick breakdown covering the laws, key terms (incident ray, normal, angle of incidence, etc.), real-world examples, and how reflection shows up in tech like optical fibers, periscopes, and telescopes. Might be a useful refresher if you're studying optics:

https://notesforphysics.com/reflection-of-light/

Most physics courses introduce spin and orbital motion as separate ideas — but they're not. They constantly talk to each other inside every atom, and that "conversation" is what makes platinum useful in hard drives and what might power the memory chips of the future.

This note breaks down spin-orbit coupling from the ground up — from Thomson's cathode-ray discovery to the Stern-Gerlach experiment, Schiff's 1955 formula, and modern spintronic effects such as the spin Hall effect, DMI, and MRAM.

Written from the electron's perspective, which makes it surprisingly fun to read.

https://notesforphysics.com/spin-orbit-coupling-electron-moments/