The exam at a glance
| Section | Weight | Timing | What you do |
|---|---|---|---|
| I · Multiple choice | 50% | 1 hr 25 min · 42 questions | Single questions and short sets built around a stimulus such as a diagram, graph or data table. Calculator allowed. |
| II · Free response | 50% | 1 hr 35 min · 4 questions | Four question types: Mathematical Routines, Translation Between Representations, Experimental Design and Analysis, and Qualitative/Quantitative Translation. |
Click in Bluebook, write on paper
You answer multiple-choice questions and read the free-response questions in the Bluebook app, then handwrite free-response answers in a paper booklet.
Equation sheet + calculator
A table of equations and constants is provided, and a calculator is allowed throughout. Knowing when an equation applies, and its conditions, matters more than memorizing it.
The multiple-choice section
42 questions in 85 minutes gives you about 2 minutes per question. Many questions test reasoning with symbols and graphs rather than plugging in numbers. Wrong answers lose no points.
Strategies that work
- Draw a diagram for every question: forces, fields, circuits or rays. It prevents sign errors.
- Check limiting cases. What happens if a mass is zero or an angle is 90°? Wrong choices often fail this test.
- Use units to eliminate answer choices with the wrong dimensions.
- Read graphs as relationships: slope and area under the curve both have physical meaning.
- Work symbolically first, then plug in numbers only if needed.
- Flag and move on after 3 minutes. Return once the quick points are banked.
The 6 units, in plain English
Electric Charges, Fields & Gauss's Law
Charges and the fields they create.
Be ready to: Apply Coulomb's law; integrate to find fields of continuous charge distributions; use Gauss's law for spheres, cylinders and planes.
Electric Potential
Energy per charge.
Be ready to: Relate field and potential (E = −dV/dx); calculate potential of point and continuous charges; find potential energy of charge systems.
Conductors & Capacitors
Storing charge and energy.
Be ready to: Describe charge on conductors in equilibrium; calculate capacitance; combine capacitors; include dielectrics; find stored energy.
Electric Circuits
Current, resistance and RC circuits.
Be ready to: Use Kirchhoff's rules on multi-loop circuits; analyze RC circuits with exponential charging and discharging; calculate power.
Magnetic Fields & Electromagnetism
Magnetic forces and the fields of currents.
Be ready to: Find forces on moving charges and currents; use the Biot-Savart law and Ampère's law for wires and solenoids.
Electromagnetic Induction
Changing flux and inductors.
Be ready to: Apply Faraday's and Lenz's laws; analyze motional emf; describe inductance and LR circuits; analyze LC oscillations qualitatively.
Units are numbered 8–13 because they continue on from Physics C: Mechanics (Units 1–7), and mechanics ideas such as forces, energy and Newton's laws are used throughout. Expect integrals for continuous charges and differential equations for RC and LR circuits.
The 4 free-response questions
95 minutes, 4 questions. The four question types are the same every year, so you can practice each on purpose. Mathematical Routines and lab questions are typically worth the most points.
Mathematical Routines
Use equations and principles to derive expressions and calculate quantities, often starting symbolically.
Start from a fundamental equation and show each substitution.
Translation Between Representations
Draw a free-body diagram, energy bar chart or graph, then write equations that are consistent with it.
Arrows on free-body diagrams start on the object and are labeled.
Experimental Design and Analysis
Design a procedure, choose what to graph to get a straight line (linearize), then use the slope to find a quantity.
Linearize: graph the quantities that make y = mx a straight line.
Qualitative/Quantitative Translation
Explain a situation in words with physics reasoning, then derive an equation that agrees with your explanation.
Make sure your words and your equation predict the same trend.
Time plan: About 25 minutes for MR, 22 for TBR, 25 for LAB and 23 for QQT. Points are given for derivations: "plugging in" without a starting equation often loses credit.
Habits that earn points
- Answer every lettered part, in order, with a label.
- Show the equation, the substitution and the units.
- Justify with a cause → effect sentence, not a word.
- Use the reference sheet; you don't need to memorize it.
- Blank part? Write the relationship you would use. It can earn credit.
10 traps that cost points
Field inside a conductor
In electrostatic equilibrium, E = 0 inside a conductor and any excess charge sits on the surface.
Gauss's law without symmetry
Gauss's law is always true, but it only gives E easily when symmetry makes E constant on the surface.
Sign of E = −dV/dx
The field points toward decreasing potential.
Capacitor combinations
Capacitors add directly in parallel and as reciprocals in series, the opposite of resistors.
RC behavior at t = 0 and ∞
An uncharged capacitor acts like a wire at t = 0 and like an open circuit after a long time.
Inductor behavior
An inductor resists changes in current: open-circuit-like at t = 0, a plain wire after a long time.
Right-hand rule for wires
Thumb along the current; fingers curl in the direction of B around the wire.
Lenz's law direction
The induced current opposes the change in flux, not the flux itself.
Ampère's law path
Choose a loop where B is constant and parallel to the path, and count only the current enclosed.
Plugging in too early
Derive symbolically first. Many questions ask for answers "in terms of" given quantities.
A study roadmap to May
A steady plan beats a last-minute rush. Shift the months to match your teacher's pacing.
- Sep – Oct
Unit 8: fields
Coulomb's law, fields of continuous charges by integration, and Gauss's law for every symmetry.
- Nov – Dec
Units 9–10: potential and capacitors
Potential from fields, conductors, capacitance and dielectrics. Start one free-response question per week.
- Jan – Feb
Unit 11: circuits
Kirchhoff's rules and RC circuits with differential equations.
- Mar – Apr
Units 12–13: magnetism and induction
Biot-Savart, Ampère, Faraday, Lenz, inductors and LR circuits. Begin full timed sections in April.
- Early May
Free-response drills
All four question types under timing, focusing on Gauss and Ampère derivations.
- May 2027
Exam day
Wednesday, May 5, 2027 (afternoon session). Sleep well and confirm your start time with your AP coordinator.
3 practice questions
Original questions written by ACT SAT GO in the style of the exam. The free PDF has 10, with full explanations.
- Unit 8 · Gauss's law
A uniformly charged solid sphere (radius R, charge Q) has field E₀ at its surface. What is the field at r = R/2?
- A E₀/4
- B E₀
- C 2E₀
- D E₀/2
Show answer
Answer: D · E₀/2. Inside a uniform solid sphere, E = Qr/(4πε₀R³) grows linearly with r. Half the radius gives half the surface field.
- Unit 10 · Capacitors
A parallel-plate capacitor is charged and then disconnected from the battery. The plate separation is doubled. What happens to the stored energy?
- A It halves
- B It doubles
- C It stays the same
- D It quadruples
Show answer
Answer: B · It doubles. Isolated, so Q is constant. Doubling d halves C. U = Q²/(2C), so U doubles; the extra energy comes from the work done pulling the plates apart.
- Unit 13 · Faraday's law
The flux through a 50-turn coil is Φ = 0.02t² (Wb per turn). What is the magnitude of the induced emf at t = 3 s?
- A 0.12 V
- B 0.18 V
- C 6.0 V
- D 9.0 V
Show answer
Answer: C · 6.0 V. emf = N dΦ/dt = 50 × 0.04t = 50 × 0.12 = 6.0 V at t = 3 s. Choice A forgets the 50 turns.
How students score
Ranges reflect recent College Board score distributions and shift a little each year. Credit and placement policies vary by college.
Aiming for a 5 in AP Physics C: Electricity and Magnetism?
Book a free diagnostic session. We'll find your weakest units, review your practice responses and give you a week-by-week plan to exam day.