Calculus-based electricity and magnetism — fields, circuits, and Maxwell's equations in integral form.
Study guide last reviewed September 25, 2026 · see what changed
Format reflects the current published structure — always confirm against AP Central before test day, since formats occasionally change.
| Section | Details | Time | Weight |
|---|---|---|---|
| Section I – Multiple Choice | 35 questions | 45 min | 50% |
| Section II – Free Response | 3 questions | 45 min | 50% |
Straight answers about the AP Physics C: Electricity and Magnetism exam — format, credit, dates, and this site.
Section I – Multiple Choice: 35 questions (45 min, 50% of the total score); Section II – Free Response: 3 questions (45 min, 50% of the total score). See the Exam Format tab above for the full breakdown, and always double-check the current year's format on AP Central before test day.
It's multiple-choice questions and written free-response or essay questions.
It depends entirely on the college — most award credit for a 3 or higher, but many selective schools require a 4 or a 5, and some don't grant credit at all for certain scores. Always check your target college's own AP credit policy page rather than assuming a 3 will count everywhere.
AP exams are administered during the College Board's annual testing window in the first two full weeks of May, with the exact date and time for each subject set by the College Board and announced the preceding fall. Check AP Central or your school's AP coordinator for this year's exact date.
Yes. The unit-by-unit study guide, worked examples, practice quiz, and full-length timed practice exam on this page are all free, with no login, signup, or paywall.
Unit-by-unit breakdown of what the course actually covers, in teaching order.
Coulomb's law and electric field from continuous charge distributions calculated via integration, and Gauss's law (∮E·dA = Qenc/ε0) as a powerful shortcut for high-symmetry situations (spheres, infinite cylinders, infinite planes) where the enclosed charge and symmetry let you solve for E algebraically instead of integrating directly.
Conductors in electrostatic equilibrium (E = 0 inside, excess charge on the surface, field perpendicular to the surface), capacitance (C = Q/V) for parallel-plate capacitors derived from Gauss's law, energy stored in a capacitor (U = ½CV² = ½QV = Q²/2C), and how inserting a dielectric increases capacitance by reducing the effective field between plates.
RC circuits analyzed with differential equations, deriving the exponential charging/discharging curves (Q(t) = Q0(1 - e^(-t/RC)) for charging) and the time constant τ = RC representing the characteristic timescale, extending algebra-based circuit analysis (which only handles steady-state) to transient behavior.
The Biot-Savart law and Ampere's law (∮B·dl = μ0 Ienc) as the two methods for calculating magnetic fields from current distributions, with Ampere's law providing shortcuts for high-symmetry cases (long straight wires, solenoids) similar to how Gauss's law simplifies electric field calculations. Forces on moving charges and current-carrying wires in magnetic fields, including circular motion of charged particles.
Faraday's law (EMF = -dΦ/dt) and Lenz's law applied to more complex, calculus-based scenarios than the algebra-based course, self-inductance and mutual inductance in circuits with inductors, LR and LC circuit behavior, and Maxwell's equations as the unifying framework connecting electricity and magnetism.
Concrete, fully worked examples — this is what separates a page reviewers see as genuinely useful from one that just lists topics.
Gauss's law: find the electric field at distance r outside a uniformly charged sphere of total charge Q and radius R (r > R).
By symmetry, choose a spherical Gaussian surface of radius r: ∮E·dA = E(4πr²) = Qenc/ε₀ = Q/ε₀. Solving: E = Q/(4πε₀r²) — identical to a point charge formula, which is exactly the point: outside a spherically symmetric distribution, all the charge behaves as if concentrated at the center.
Parallel-plate capacitor: derive capacitance for plates of area A separated by distance d, then find the energy stored at voltage V.
From Gauss's law, E = σ/ε₀ = Q/(Aε₀), and V = Ed = Qd/(Aε₀), so C = Q/V = ε₀A/d. Energy stored: U = ½CV². Inserting a dielectric with constant κ multiplies C (and thus the stored energy at fixed voltage) by κ.
RC charging: a capacitor charges through a resistor with time constant τ = RC. What fraction of full charge is reached at t = τ?
Q(t) = Q₀(1 − e−t/RC). At t = τ = RC: Q = Q₀(1 − e⁻¹) ≈ 63.2% of full charge — this specific percentage at exactly one time constant is a frequently tested numerical fact, not something you need to re-derive under time pressure.
Ampere's law: find the magnetic field at distance r from a long straight wire carrying current I.
Choose a circular Amperian loop of radius r: ∮B·dl = B(2πr) = μ₀Ienc = μ₀I. Solving: B = μ₀I/(2πr). Ampere's law is the magnetic parallel to Gauss's law — both are shortcuts that only work when the symmetry of the situation matches the shortcut (cylindrical here, spherical/planar for Gauss's law).
LC circuit: an inductor L and capacitor C oscillate together. Set up the governing differential equation and identify the angular frequency.
Energy conservation gives L(d²Q/dt²) + Q/C = 0, a simple harmonic motion equation analogous to a spring-mass system. Its angular frequency is ω = 1/√(LC) — recognizing the direct analogy to mechanical SHM (mass↔L, spring constant↔1/C) makes this unit far more intuitive than memorizing it as a new formula.
The errors that cost the most points across the whole exam, not just one unit.
Unofficial practice questions written for this study guide — not official AP content and not from College Board. Use them to self-check, then use the real past free-response questions below for authentic exam practice.
Unofficial practice, timed to feel like the real thing. Section I pulls from this page's full multiple-choice bank; Section II gives you free-response prompts to write out and self-score against a rubric. Bank size is still growing toward full exam length — timing is paced per-question, not pulled from this subject's official duration.