🔭 Optics
The physics of light: reflection, refraction, lenses, mirrors, polarization and interference.
What you will learn
- Trace rays through mirrors and lenses
- Use Snell's law at boundaries
- Predict image position and magnification
- Explain polarization and interference of light
Study guide
High School concepts
Fiber Optics Explained — How Hair-Thin Glass Carries the Internet
A fiber-optic cable guides light for kilometers using total internal reflection. Learn about core and cladding, the acceptance cone, single vs multimode…
Lenses and Image Formation — Converging vs Diverging
Converging and diverging lenses: the thin lens equation 1/f = 1/do + 1/di, ray diagrams, magnification, and how cameras and glasses use lenses.
Mirrors and Image Formation — Concave vs Convex
Concave and convex mirrors: how curved mirrors form real and virtual images, the mirror equation 1/f = 1/do + 1/di, and ray diagrams explained.
Optical Instruments — Cameras, Microscopes, Telescopes
Optical instruments explained: how cameras, microscopes, telescopes, and magnifiers use lenses and mirrors — with ray logic and magnification.
Polarization of Light — Filters, Malus's Law, Sunglasses
Light polarization explained: transverse waves, polarizing filters, Malus's law I = I₀cos²θ, and why polarized sunglasses kill glare.
Ray vs Wave Optics — Two Models of Light and When to Use Each
Ray optics treats light as straight rays; wave optics treats it as waves. The key difference is scale — rays suit lenses and mirrors; waves explain diffraction and interference.
Refraction and Snell's Law — Why Light Bends
Snell's law of refraction: n₁sinθ₁ = n₂sinθ₂. Learn why light bends at boundaries, how lenses work, and why pools look shallower than they are.
Total Internal Reflection — Critical Angle and Fiber Optics
Total internal reflection: when light cannot escape glass or water, the critical angle sin θc = n₂/n₁, and how fiber optics trap light.
Introductory College concepts
Interference and Diffraction of Light — Double Slit Explained
Wave interference and diffraction: constructive vs destructive interference, Young's double slit, single-slit diffraction, and diffraction gratings.
How Lasers Work — Stimulated Emission and the Optical Cavity
Ordinary light is chaotic; laser light is synchronized. Learn how stimulated emission, population inversion and a mirrored cavity turn random photons into a…
Beginner concepts
Formulas
Lens Equation — 1/f = 1/do + 1/di
The reciprocals of image distance and object distance add up to the reciprocal of the focal length.
m = −dᵢ/dₒ — Lens Magnification
Magnification equals image height over object height, or negative image distance over object distance.
Snell's Law — n₁sinθ₁ = n₂sinθ₂
The product of refractive index and sine of the angle is conserved across a boundary.
Calculators
Simulations
Practice
Optical Instruments Practice
10 problems · 10 practice problems on optical instruments — microscopes, telescopes, cameras and the human eye.…
Lenses Practice 2
10 problems · 10 practice problems on lenses — converging and diverging image formation, power and magnification.…
Mirrors Practice
10 problems · 10 practice problems on mirrors — plane, concave and convex image formation and ray diagrams.…
Optics Practice — Reflection, Refraction and Lenses
10 problems · 10 practice problems on optics — reflection, refraction, Snell's law, lenses and mirrors — with full…
Polarization Practice
10 problems · 10 practice problems on polarization — polarizers, Malus's law, Brewster's angle and applications.…
Refraction Practice 2
10 problems · 10 practice problems on refraction — Snell's law, critical angle, total internal reflection and disp…
Wave Optics Practice
10 problems · 10 practice problems on wave optics — diffraction, thin-film interference, gratings and resolution.…