▸ Sciences · Physics

Physics

From a falling apple to F = −kx to ∂L/∂q̇ — the universe in equations, intuition, and worked problems.
2,840topics
14problem libraries
7exam tracks
+312trending this week

By topic

browse the canon · choose where to start
Classical mechanics
F = ma · ½mv² · L = T − V
Newton's laws, energy, oscillations, rigid bodies, Lagrangian. The foundation.
142 topicstrending
Electricity & magnetism
∇·E = ρ/ε₀ · ∇×B = μ₀J + …
From Coulomb's law to Maxwell — the road to electromagnetic waves and light.
186 topics
Quantum mechanics
iℏ ∂ψ/∂t = Ĥψ
Postulates, operators, spin, perturbation theory. From "what is wave-particle?" to ladder operators.
204 topicstrending
Thermodynamics & stat mech
dS ≥ dQ/T · Z = Σ e^(−βE)
Heat, entropy, partition functions. Why ice melts and why time has a direction.
128 topics
Optics & waves
n₁ sin θ₁ = n₂ sin θ₂
Reflection, refraction, interference, diffraction. Light as wave and ray.
94 topics
Relativity
E² = (pc)² + (mc²)² · ds² = …
Special and general — clocks, geodesics, why gravity is geometry.
86 topics
Solid state & condensed matter
k-space · band structure · phonons
Why metals conduct, why semiconductors switch, why magnetism happens.
132 topics
Particle physics & QFT
ℒ = ψ̄(iγ^μ ∂_μ − m)ψ + …
Standard model, gauge fields, Feynman diagrams. The deep end.
112 topics

Problem libraries

canonical sources · solve, struggle, ask
Irodov · Problems in General Physics
The legendary Russian problem book. Mechanics, optics, thermo, modern physics.
★★★★★ · 1,920 problems · solutions on demand
Griffiths · Intro to Electrodynamics
The undergrad standard for E&M. Worked examples + end-of-chapter sets.
★★★★★ · 580 problems · grad-track variant
Goldstein · Classical Mechanics
Lagrangian / Hamiltonian. The grad-school benchmark.
★★★★☆ · 410 problems · grad
Halliday-Resnick
Big intro textbook. Wide coverage, accessible, tons of variants.
★★★★☆ · 2,100 problems · HS+UG
Sakurai · Modern QM
Operator-first approach. The grad-level QM standard.
★★★★★ · 320 problems · grad
MIT OpenCourseWare problem sets
8.01, 8.02, 8.03, 8.04. Real psets with solutions.
★★★★★ · 8 courses · UG

Exam prep

targeted · timed · performance-tracked
JEE MainIndia · undergrad-engMechanics + E&M + modern physics. Problem-heavy.
JEE AdvancedIndia · IIT trackHigher rigor than Main. Multi-step problems.
NEETIndia · medicalHS-level physics — concept-heavy, light math.
AP PhysicsUS high school1, 2, C-Mech, C-E&M tracks.
Olympiadnational + IPhOHardest pre-college physics on Earth. Theory + experiment.
Physics GREgrad school100 MCQs · all of UG physics in 3 hours.
A-levelsUK · pre-undergradCambridge / Edexcel boards.

By level

match your background · move up or down anytime
▸ entryPop physicsCurious, no math required. "Why is the sky blue?" energy.~250 topics
▸ HSHigh schoolAlgebra-based · Newton's laws, electricity, optics. NCERT/AP Physics 1.~620 topics
▸ UGUndergradCalculus + intro vector analysis. Halliday/Griffiths level.~1,140 topics
▸ gradGraduateGoldstein, Jackson, Sakurai. Tensors, group theory, QFT.~830 topics

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