AP Physics C: Electricity and Magnetism — “E&M” — is the calculus-based electromagnetism course, and it’s often called the hardest AP exam of all. It’s the second-semester partner to Physics C: Mechanics, with even heavier calculus: Gauss’s law, the Biot–Savart law, electric flux, and induction. A recent redesign made it a full-length exam in its own session, pairing 40 multiple-choice questions with 4 free-response questions. This guide breaks the whole exam down: the two sections, the five units, the calculus, scoring, and how it differs from the algebra-based Physics 2.
The essentials: the AP Physics C: E&M exam has two equally-weighted sections and runs about 3 hours. Section I = 40 multiple-choice in 80 minutes (50%) — single-select, four choices, digital in Bluebook. Section II = 4 free-response in 100 minutes (50%), handwritten, 40 points, each testing a different science-practice skill. The defining feature: it’s calculus-based — and the calculus is heavier than in Mechanics (vector calculus, Gauss’s law, the Biot–Savart law, electric flux, induction). It covers electromagnetism in five units, equivalent to a second-semester calculus-based college E&M course, and Mechanics is its functional prerequisite (E&M’s units are numbered 8–13, continuing after Mechanics’s seven). A calculator and equation sheet are permitted on both sections; MCQ has no wrong-answer penalty; FRQ gives partial credit. It’s hybrid digital, scored 1–5, now a full-length exam in its own session, and widely regarded as one of the most demanding AP exams. Here’s the full breakdown.
Once you know the sections and weights, run your practice numbers through the AP score calculator. E&M builds on Mechanics — start with the AP Physics C: Mechanics exam guide, and see how long the Physics C exams are.
What this guide covers
The AP Physics C: E&M exam at a glance
Start with the overall shape, because after the recent redesign this exam matches the other AP Physics exams structurally — but with the heaviest calculus of the four. Two equal sections, about three hours.
The AP Physics C: E&M exam is built around two sections of equal weight: Section I is 40 multiple-choice questions (50%) and Section II is 4 free-response questions (the other 50%), for a total testing time of about 3 hours. Its defining characteristics: it’s a calculus-based course — and its calculus is the most demanding of the four AP Physics exams, involving vector-calculus concepts like flux and line integrals. It’s the calculus-based treatment of electromagnetism, the second-semester partner to Physics C: Mechanics. It’s a hybrid digital exam: multiple-choice on a computer in the Bluebook app, free-response handwritten in a paper booklet. The content covers electricity and magnetism — electrostatics, electric potential, capacitance, magnetic fields, and induction — organized into five units, and it’s equivalent to a second-semester calculus-based college E&M course for physics and engineering majors. A calculator is permitted on both sections and an equation sheet is provided. One important structural note: after the recent redesign, AP Physics C: E&M is now a full-length exam in its own dedicated testing session — previously it was a shorter exam sharing a session with Mechanics. And one reputational note worth stating up front: E&M is widely considered one of the hardest AP exams, because of its combination of heavy calculus and abstract content. The most important framing: this is the calculus-based electromagnetism exam, structurally like the other AP Physics exams but distinguished by its advanced calculus and its focus on rigorous, college-level E&M. The sections below break down each part.
The core point: AP Physics C: E&M = 40 multiple-choice (80 min, 50%) + 4 free-response (100 min, 50%), about 3 hours, and crucially calculus-based with the heaviest math of the four AP Physics exams (Gauss’s law, Biot–Savart, flux). It covers electromagnetism in five units, equivalent to a second-semester calculus-based college course, and builds on Physics C: Mechanics. Now a full-length exam in its own session.
The (heavier) calculus requirement
What defines AP Physics C: E&M — and what makes it so demanding — is that its calculus is even heavier than Mechanics’s. Vector calculus, applied to fields.
Like Mechanics, AP Physics C: E&M is calculus-based — but its calculus is heavier and more advanced, which is central to its difficulty. Calculus is woven throughout to handle electromagnetism, and it involves more abstract, multi-dimensional mathematics than Mechanics. Concretely, you’ll use integration and Gauss’s law to find electric fields from charge distributions, integrate fields to find electric potential, apply the Biot–Savart law and Ampere’s law for magnetic fields, and work with changing flux in electromagnetic induction. Much of this involves vector-calculus concepts — flux (integrating a field over a surface) and line integrals — which are more mathematically demanding than the calculus in Mechanics, where you’re often differentiating and integrating functions of a single variable. This calculus appears in both the multiple-choice and free-response sections. Because of this, the course has a clear expectation: students should have taken or be concurrently taking calculus, and ideally have a strong calculus foundation, since E&M’s mathematics is more abstract than Mechanics’s. This heavier, more abstract calculus is a major reason AP Physics C: E&M is considered one of the hardest AP exams — it fuses challenging electromagnetism concepts (invisible fields, flux, induction) with advanced calculus. It’s also what most distinguishes E&M from the algebra-based AP Physics 2, which covers some similar topics but without calculus. The practical implication: strong calculus skills, especially with integration and the concept of flux, are essential — arguably even more so than in Mechanics. For the full difficulty picture, see the difficulty guide once it’s live; for now, the takeaway is that E&M’s calculus is its defining challenge.
Why Mechanics comes first
AP Physics C: E&M isn’t usually a standalone starting point — it builds on Mechanics, and the course design makes that explicit. A second course, not a first.
An important thing to understand about AP Physics C: E&M is that Mechanics is functionally its prerequisite — E&M is the second course in the Physics C sequence, not usually a starting point. The clearest evidence, exactly as with the Physics 1→2 sequence, is the unit numbering: E&M’s units are numbered starting at 8 (Electric Charges, Fields, and Gauss’s Law is Unit 8), continuing directly after Physics C: Mechanics’s seven units. This is a deliberate signal that Mechanics comes first and E&M builds on it. What Mechanics provides that E&M assumes: the calculus-based physics problem-solving foundation, the mathematical maturity, and the familiarity with the exam’s style and rigor. In practice, most students take Mechanics first (often in the same year or the year before) and then E&M, and many colleges and courses treat the two as a sequence. The College Board also recommends students be taking or have taken calculus for both. So the practical implication: if you’re planning to take E&M, you should generally take (or have taken) Physics C: Mechanics first, and be solid with calculus. Taking E&M without the mechanics foundation and without calculus would be very challenging. This also sets up a natural comparison — how the two Physics C exams differ — which is worth exploring on its own once you know both. For the first course in the sequence, see the AP Physics C: Mechanics exam guide.
How AP Physics C: E&M differs from Physics 2
Because both cover electricity and magnetism, students often confuse E&M with Physics 2 — but they’re very different exams. Deeper and calculus-based vs. broader and algebra-based.
AP Physics C: E&M and AP Physics 2 overlap in their electricity and magnetism content (electrostatics, capacitors, circuits, magnetism, induction), which causes confusion — but they differ in two major ways. First, the math: AP Physics C: E&M is calculus-based, using calculus (including vector calculus like Gauss’s law and the Biot–Savart law) to treat electromagnetism with mathematical depth, while AP Physics 2 is algebra-based, covering similar topics without calculus. This makes E&M far more mathematically demanding. Second, the scope: AP Physics C: E&M focuses only on electromagnetism and goes much deeper into it (electric flux, inductance, RL and LC circuits, Maxwell’s equations), while AP Physics 2 is broader — it covers thermodynamics, optics, waves, and modern physics in addition to its single electricity-and-magnetism unit. So the contrast is clear: E&M is narrower but much deeper and calculus-based; Physics 2 is wider-ranging but algebra-based. They also serve different audiences: E&M is aimed at calculus-ready students planning physics or engineering (and is recognized by more universities for that purpose), while Physics 2 suits a broader audience wanting a survey of second-semester physics without calculus. And on difficulty, E&M is generally considered significantly harder than Physics 2, primarily because of the calculus. So which to take? If you’re calculus-ready and STEM-bound and want depth in electromagnetism, E&M; if you want a broader, algebra-based second-semester survey, Physics 2. For that course, see the AP Physics 2 exam guide, and for the algebra-based sequence, AP Physics 1 vs 2.
The multiple-choice section
Half your score rides on the multiple-choice section, which tests calculus-based electromagnetism reasoning across all five units. 40 questions, 80 minutes.
Section I is 40 multiple-choice questions in 80 minutes, worth 50% — about 2 minutes per question. Each is single-select with four answer choices (reduced from five in the redesign), appearing as discrete questions or in sets sharing a stimulus (a scenario, circuit diagram, field diagram, graph, or data). Critically, this is a calculus-based section covering abstract electromagnetism: many questions require calculus reasoning (integration, flux, field calculations) and conceptual understanding of invisible fields, and are often multi-step — making them among the more challenging AP multiple-choice questions. Two practical points. First, a calculator is permitted on the multiple-choice section and an equation sheet is provided — get familiar with both. Second, there’s no penalty for wrong answers, so answer every question, using elimination and educated guessing when unsure. Because many questions are multi-step and mathematically demanding, pacing matters: don’t go strictly in order — solve the questions you can do quickly first, flag the harder multi-step ones, and return to them. The section rewards fluency with both the electromagnetism concepts and the calculus. For how to drill it, see the practice guide once it’s live.
The free-response section
The other half of your score comes from four handwritten questions, each targeting a specific science-practice skill and requiring full calculus-based derivations. Show reasoning, show calculus.
Section II is 4 free-response questions in 100 minutes — about 25 minutes each — worth the other 50%, totaling 40 points (each point equals one point, matching the 40 multiple-choice questions for an 80-point composite). You view the prompts on screen but handwrite your answers in a paper booklet scored by trained AP Readers. Like the other AP Physics exams, the four questions each test a different science-practice skill: Mathematical Routines (deriving and applying relationships and doing calculations, often with calculus), Translation Between Representations (moving among words, equations, graphs, diagrams, and field/circuit representations), Experimental Design and Analysis (designing a procedure, identifying variables, and analyzing data, often with graphing), and Qualitative/Quantitative Translation (connecting conceptual reasoning with math and justifying claims). Each question is multi-part and scored with partial credit for correct steps, reasoning, and work — so showing your full process is essential, and you should attempt every sub-part. Because it’s calculus-based E&M, expect to derive expressions — for instance, deriving an expression for a field or potential using Gauss’s law or integration. Several habits pay off: use the calculator, ruler/straightedge, and equation sheet; label parts clearly; graph carefully (labeled axes and units); justify claims with reasoning beyond just equations; and include units. For practice strategy, see the practice guide once it’s live.
The five units
Knowing the units — all treated with calculus and numbered to follow Mechanics — helps you see the shape of the course. Five units of electromagnetism.
The AP Physics C: E&M course covers electromagnetism in five units, all treated using calculus, and numbered to continue after Mechanics’s seven units: Unit 8 Electric Charges, Fields, and Gauss’s Law, Unit 9 Electric Potential, Unit 10 Conductors and Capacitors, Unit 11 Magnetic Fields, and Unit 12 Electromagnetism (electromagnetic induction). These cover electrostatics, electric potential and capacitance, magnetic fields and forces, and electromagnetic induction — using calculus-heavy tools like electric flux, Gauss’s law, the Biot–Savart law, and Ampere’s law. On weighting: Electric Charges, Fields, and Gauss’s Law is typically the most heavily weighted unit, with the others carrying substantial weight too. The unit bars below show the approximate weight ranges. The practical implication: while all units are tested, give priority to the higher-weighted units — especially the foundational Electric Charges, Fields, and Gauss’s Law. Confirm the current weight ranges in the official Course and Exam Description. For where to find that, see the practice guide once it’s live.
Scoring and logistics
Pulling the structure together into the score and the practical exam-day details completes the picture. Weighted 50/50, scored 1–5.
Scoring is on the 1 to 5 scale, with the two sections weighted equally at 50% each. The 40 multiple-choice questions are computer-scored — each correct answer earns a point, no penalty for wrong answers — while the 4 free-response questions are hand-scored by trained AP Readers using rubrics, worth 40 points total, with partial credit for correct steps, reasoning, and work (including calculus derivations). The two combine into a composite score converted to a 1–5 using that year’s cut points. On logistics: it’s a hybrid digital exam, so you’ll need a charged device with the Bluebook app (and a power cord), plus photo ID, pencils and pens (black or dark blue ink), an approved calculator, and a ruler/straightedge can help. The equation/reference sheet is provided in the app. Remember it’s in its own dedicated testing session (separate from Mechanics, and on a different day). Two strategy takeaways: because there’s no wrong-answer penalty, answer every multiple-choice question; and because free response awards partial credit, attempt every part, show all your work (including calculus derivations), and include units. One notable point about E&M’s scores: it often has a relatively high proportion of top scores, reflecting its self-selected, well-prepared, calculus-ready student population — a strong pass rate that coexists with genuinely hard material. To turn section performance into a predicted score, use the AP score calculator; for the mechanics of AP scoring, see how AP exams are scored, and for what to bring, AP exam day essentials.
| Section | Questions | Time | Weight | Format |
|---|---|---|---|---|
| Section I — Multiple choice | 40 | 80 min | 50% | Digital (Bluebook) |
| Section II — Free response | 4 (40 pts) | 100 min | 50% | Handwritten (paper) |
| Total | 44 | ~3 hours | 100% | Hybrid |
Calculus-based; calculator and equation sheet provided both sections; no penalty for wrong MCQ answers; FRQ scored with partial credit. In its own testing session (separate day from Mechanics). Reflects the current redesigned exam — the MCQ count and timing change for May 2027. Confirm with the College Board.
The redesign and what’s changing next
AP Physics C: E&M changed significantly and is set to change again, so it’s important to know which format applies to you. A major restructuring, plus more coming.
AP Physics C: E&M has been significantly restructured, and there’s another change on the way. The redesign, introduced starting with the 2024–25 school year, made this exam a full-length exam in its own dedicated testing session — a big change from the previous shorter format, in which E&M was one of the shortest AP exams and shared a testing day with Mechanics. Specifically: the multiple-choice section went from 35 questions in 45 minutes to 40 questions in 80 minutes, the answer choices went from five to four, and the free-response section went from 3 questions in 45 minutes to 4 questions in 100 minutes, with new standardized question types (the same four science-practice types across all AP Physics exams). The exam is now the same length as AP Physics 1 and 2. Importantly, the content itself did not change substantially — this was primarily a structural update reflecting that E&M is a full college-semester course in its own right. On top of this, the College Board has announced that the number of multiple-choice questions and the timing for each section will be updated again starting with the May 2027 exam (with the multiple-choice section moving to a slightly different question count and section timing). What this means for you: the format described throughout this guide reflects the current redesigned exam — but if you’re testing in May 2027 or later, confirm the updated question count and timing on the College Board’s official page. It also means older prep materials may show the old shorter format (35 MCQ/45 min, 3 FRQ/45 min, five answer choices) — and importantly, old released free-response exams no longer match the current structure — so make sure any practice resources are updated for the current exam. The most reliable source is the College Board’s official AP Physics C: E&M page and Course and Exam Description. For confirming timing, see how long the Physics C exams are (E&M matches Mechanics’s current timing).
Note on changes: AP Physics C: E&M was recently restructured into a full-length exam in its own session (40 MCQ/80 min + 4 FRQ/100 min, four answer choices), up from the old shorter shared-session format. The College Board has also announced that the number of multiple-choice questions and the timing will be updated again starting with the May 2027 exam (moving toward a slightly different MCQ count and section timing). The format here reflects the current exam. If testing in May 2027 or later, confirm the updated numbers on the College Board’s official page, and make sure any older prep materials (especially released FRQs) match the current format.
AP Physics C: E&M exam: frequently asked questions
What is on the AP Physics C: Electricity and Magnetism exam?
Two equally weighted sections, about 3 hours total. Section I is 40 multiple-choice questions in 80 minutes, worth 50%, single-select with four answer choices, done digitally in Bluebook. Section II is 4 free-response questions in 100 minutes, also 50%, handwritten. AP Physics C: E&M is a calculus-based course, using calculus throughout, and it covers electromagnetism in five units: electric charges, fields, and Gauss’s law; electric potential; conductors and capacitors; magnetic fields; and electromagnetism (electromagnetic induction). It’s equivalent to a second-semester calculus-based college course in electricity and magnetism for physics and engineering majors. A calculator and equation sheet are permitted on both sections. The four free-response questions each test a different science-practice skill. It’s scored 1 to 5. Note that AP Physics C: E&M is now a full-length exam in its own testing session, following a recent redesign, and it’s widely regarded as one of the most demanding AP exams because of its heavy calculus and abstract content.
Is AP Physics C: E&M calculus-based?
Yes, and its calculus is actually heavier and more advanced than in AP Physics C: Mechanics. The course uses calculus throughout to handle electromagnetism: for example, using integration and Gauss’s law to find electric fields from charge distributions, calculating electric potential by integrating fields, using the Biot-Savart law and Ampere’s law for magnetic fields, and working with changing flux in electromagnetic induction. This involves vector-calculus concepts like flux and line integrals, which makes the mathematics more demanding than in Mechanics. Because of this, students should have taken or be concurrently taking calculus, and ideally should have a strong calculus foundation, since E&M’s mathematics is more abstract. This is a key reason AP Physics C: E&M is considered one of the hardest AP exams. It also distinguishes E&M from the algebra-based AP Physics 2, which covers some similar electricity and magnetism topics but without calculus.
What is the difference between AP Physics C: E&M and AP Physics 2?
They overlap in electricity and magnetism content (electrostatics, capacitors, circuits, magnetism, induction), but differ in two major ways. First, AP Physics C: E&M is calculus-based, using calculus (including vector calculus like Gauss’s law and the Biot-Savart law) to treat electromagnetism with mathematical depth, while AP Physics 2 is algebra-based, covering similar topics without calculus. This makes E&M far more mathematically demanding. Second, the scope differs: AP Physics C: E&M focuses only on electromagnetism and goes deeper (electric flux, inductance, RL and LC circuits, Maxwell’s equations), while AP Physics 2 is broader, also covering thermodynamics, optics, waves, and modern physics beyond its E&M unit. So E&M is narrower but much deeper and calculus-based, while Physics 2 is wider-ranging but algebra-based. E&M is aimed at calculus-ready students planning physics or engineering, while Physics 2 suits a broader audience. E&M is generally considered significantly harder.
What units are on the AP Physics C: E&M exam?
Five units, all treated with calculus: Unit 8 Electric Charges, Fields, and Gauss’s Law; Unit 9 Electric Potential; Unit 10 Conductors and Capacitors; Unit 11 Magnetic Fields; and Unit 12 Electromagnetism (electromagnetic induction). The units are numbered 8 through 13 (with electromagnetism spanning the final units) to continue consecutively after AP Physics C: Mechanics’s seven units, reflecting that Mechanics is a functional prerequisite. Electric Charges, Fields, and Gauss’s Law is typically the most heavily weighted unit. These units cover electrostatics, electric potential and capacitance, magnetic fields and forces, and electromagnetic induction, all at a calculus-based level using concepts like electric flux, Gauss’s law, the Biot-Savart law, and Ampere’s law. The official Course and Exam Description lists the exact weight ranges for each unit, which determine how many of the 40 multiple-choice questions cover each topic. All units are tested on the exam.
How is the AP Physics C: E&M exam scored?
On the 1 to 5 scale, with the multiple-choice and free-response sections weighted equally at 50% each. The 40 multiple-choice questions are computer-scored, with each correct answer earning a point and no penalty for wrong answers, so answer every question. The 4 free-response questions are hand-scored by trained AP Readers using rubrics, worth 40 points total, with partial credit for correct steps, reasoning, and work, so showing your full process, including calculus derivations, matters. The two sections combine into a composite converted to a 1 to 5 using that year’s cut points. Because there’s no wrong-answer penalty, guessing on multiple choice is always worthwhile, and because free response gives partial credit, attempt every part of every question. Clearly showing your work, including your calculus setup and derivations, and including units on numerical answers helps you earn maximum partial credit. AP Physics C: E&M often has a relatively high proportion of top scores, reflecting its self-selected, well-prepared, calculus-ready student population.
Did the AP Physics C: E&M exam change?
Yes, it was significantly restructured, and another change is coming. In the recent redesign (starting with the 2024-25 school year), the exam became a full-length exam in its own dedicated testing session, rather than the previous shorter format that shared a session with Mechanics. Specifically, the multiple-choice section went from 35 questions in 45 minutes to 40 questions in 80 minutes, the answer choices went from five to four, and the free-response section went from 3 questions in 45 minutes to 4 questions in 100 minutes, with new standardized question types. The exam is now the same length as AP Physics 1 and 2. The content itself did not change substantially. On top of this, the College Board has announced that the number of multiple-choice questions and the timing for each section will be updated again starting with the May 2027 exam (with the multiple-choice section moving to a slightly different question count and timing). So confirm which format applies to your exam year, and make sure any older prep materials, especially released free-response questions, reflect the current structure rather than the old shorter one.
The quick version
The AP Physics C: Electricity and Magnetism (E&M) exam has two equally-weighted sections and runs about 3 hours. Section I is 40 multiple-choice questions in 80 minutes (50%), single-select with four answer choices, done digitally in Bluebook. Section II is 4 free-response questions in 100 minutes (50%), handwritten, worth 40 points, each testing a different science-practice skill. The defining feature is that it’s calculus-based, with the heaviest math of the four AP Physics exams — vector calculus like Gauss’s law, the Biot-Savart law, electric flux, and induction — so a strong calculus foundation is essential. It covers electromagnetism in five units (electric charges/fields/Gauss’s law, electric potential, conductors and capacitors, magnetic fields, and electromagnetism/induction), numbered 8 through 13 to follow Mechanics’s seven units, because Mechanics is its functional prerequisite. It’s equivalent to a second-semester calculus-based college E&M course. A calculator and equation sheet are provided on both sections; there’s no penalty for wrong multiple-choice answers, and free response gives partial credit. It’s a hybrid digital exam, scored 1 to 5, now a full-length exam in its own session, and widely regarded as one of the most demanding AP exams — though its self-selected, calculus-ready student pool means a strong pass rate.
Ready to see where you stand? Estimate your score with the free AP score calculator. E&M builds on Mechanics — start with the AP Physics C: Mechanics exam guide, compare with the algebra-based AP Physics 2, browse the hardest AP exams, or explore all education calculators.
Accuracy note: AP Physics C: Electricity and Magnetism exam format, section timing, scoring, unit content and weightings, and calculator policy are set by the College Board and can change (the exam was recently restructured, and the multiple-choice count and timing update again for May 2027). The information here reflects the current exam for general informational purposes only. Always confirm the exact current format, timing, scoring, unit weightings, and approved-calculator list on the College Board’s official AP Physics C: Electricity and Magnetism page and Course and Exam Description before relying on any specific detail.
The College Board’s AP Physics C: Electricity and Magnetism exam page details the current format, sections, timing, calculator policy, and reference materials. AP Physics C: E&M exam →
The College Board’s AP Students page covers the course, the exam, and the five units. AP Physics C: E&M for students →