AP Physics C: Electricity and Magnetism Exam Instructions

The 200-word examination instruction list

AP Physics C: Electricity and Magnetism asks you to choose a model, identify the relevant geometry, and justify a direction or magnitude. Draw the surface, path or circuit before deciding whether to integrate, differentiate or use a conservation rule.

Start with the list or jump to exam requirements, worked examples, the Fencing Method or practice. The list combines task verbs with subject terms that help you interpret the question.

Essential instructions

No.	Instruction or term	Meaning or action
1	Identify	Name or pick out the item the question specifies.
2	State	Express the required point directly and clearly.
3	Describe	Report the relevant characteristics, events or pattern.
4	Explain	Connect the result to its cause, mechanism or reasoning.
5	Compare	Set the items side by side on the same relevant feature.
6	Interpret	Say what a statement, result or display means in context.
7	Justify	Give evidence for the claim and explain how that evidence supports, qualifies or defends it.
8	Evaluate	Weigh relevant evidence or criteria before reaching a judgment.
9	Determine	Work from the given information to establish an answer.
10	Calculate	Use numbers or other given information to work out a result.
11	Estimate	Find an approximate answer using the available clues.
12	Sketch	Show the required shape, relationships and labels.
13	Construct	Produce the specified representation using the information given.
14	Label	Attach the correct name to the indicated part.
15	Select	Choose only the number of options requested.
16	Check	Test the answer against the original instruction or condition.
17	Analyze	Break the information into relevant parts and explain how they relate.
18	Multiple-choice question	Select the answer that satisfies the full stem and any limiting words.
19	Free-response question	Produce your own answer and complete each labelled task.
20	Stimulus	Use the figure, extract or other material attached to the question.
21	Answer each subpart	Treat each lettered instruction as a separate job.
22	Hybrid digital	Check which questions are displayed digitally and which answers go in a paper booklet.

Subject terms and physical models

No.	Instruction or term	Meaning or action
23	Charge density	Identify charge per unit length, area or volume before choosing a differential element.
24	Charge element	Multiply the appropriate charge density by a small length, area or volume.
25	Field integral	Sum vector contributions from differential charge elements.
26	Potential integral	Sum scalar potential contributions from differential charge elements.
27	Electric dipole	A pair of equal and opposite charges separated by a distance.
28	Dipole moment	Use a vector from negative to positive charge with magnitude equal to charge times separation.
29	Electric flux	Integrate the electric field’s normal component over the chosen surface.
30	Gaussian surface	Choose a closed mathematical surface suited to the charge distribution’s symmetry.
31	Enclosed charge	Count the net charge inside the Gaussian surface.
32	Gauss’s law	Set total outward electric flux through a closed surface equal to enclosed charge divided by vacuum permittivity.
33	Spherical symmetry	Use equal field magnitude at a fixed radial distance and determine its radial direction.
34	Cylindrical symmetry	Use radial symmetry about an axis to choose a suitable cylindrical surface.
35	Planar symmetry	Use a surface crossing the plane to exploit equal magnitudes and field directions.
36	Field from potential	Take the negative spatial derivative of potential along the coordinate.
37	Potential difference integral	Integrate the negative electric-field component along the path.
38	Electrostatic boundary condition	Apply the relevant conditions just inside and outside a conductor or charged surface.
39	Surface charge density	Express charge per unit area and track whether it is uniform.
40	Electrostatic shielding	Use equilibrium charge redistribution to explain the field under the stated conductor and cavity conditions.
41	Grounding	Allow charge exchange with a reference conductor at a fixed potential.
42	Capacitor energy	Use a compatible form of one-half charge times voltage.
43	Disconnected capacitor	Treat total stored charge as fixed when there is no conducting path for charge transfer.
44	Battery-connected capacitor	Treat voltage as fixed for an ideal battery connection.
45	Effective capacitance	Combine capacitors using the correct series or parallel rule.
46	Current density	Describe current per unit area and use its direction for conventional current.
47	Resistivity	A material property used with conductor geometry to determine resistance.
48	Resistive dissipation	Use I²R for power converted to internal energy in a resistor.
49	RC time constant	Multiply equivalent resistance seen by the capacitor by capacitance.
50	Capacitor charging	Use the exponential approach toward the final capacitor voltage.
51	Capacitor discharging	Use exponential decay from the initial voltage or charge.
52	Steady-state capacitor	For a constant-source circuit after transients decay, treat an ideal capacitor branch as open.
53	Initial capacitor voltage	Use continuity of voltage across an ideal capacitor for ordinary finite currents.
54	Kirchhoff junction equation	Write current conservation using a consistent sign convention.
55	Kirchhoff loop equation	Follow a chosen loop direction and keep signs of each potential change consistent.
56	Biot–Savart law	Sum magnetic-field contributions from directed current elements.
57	Ampèrian loop	Choose a closed path convenient for evaluating the magnetic circulation.
58	Ampère’s law	Relate magnetic circulation to current enclosed in the magnetostatic case.
59	Long straight wire field	Use inverse distance dependence and a circular field direction in the ideal model.
60	Ideal solenoid	Use turns per unit length and current to find the approximately uniform interior field.
61	Magnetic force on a moving charge	Use charge times the cross product of velocity and magnetic field.
62	Magnetic force on a wire	Use the current and vector length in a uniform magnetic field.
63	Magnetic torque	Use the cross product of the magnetic dipole moment and field.
64	Faraday’s law	Find induced emf from the negative rate of change of magnetic flux linkage.
65	Flux linkage	Multiply the flux through one turn by the number of turns when each turn links the same flux.
66	Motional emf	Determine voltage arising as a conductor moves through a magnetic field.
67	Self-inductance	Relate a changing current to the emf it induces in the same circuit.
68	Inductor energy	Calculate stored magnetic energy as one-half inductance times current squared.
69	RL time constant	Divide inductance by equivalent resistance seen by the inductor.
70	Initial inductor current	Use continuity of current through an ideal inductor for ordinary finite voltages.
71	Steady-state inductor	Treat an ideal inductor as a short once direct current is constant.
72	Direction of induced current	Determine the change in flux, choose the opposing field and infer the current’s circulation.

Representations, experiments and calculations

No.	Instruction or term	Meaning or action
73	Coulomb’s law	Use the product of charges and inverse square of separation to calculate electric force.
74	Electric field	Find force per unit positive test charge.
75	Electric potential	Find electric potential energy per unit charge.
76	Potential difference	Compare electric potential between two locations.
77	Equipotential	Identify locations with the same electric potential.
78	Superposition	Add fields as vectors and electric potentials as scalars.
79	Conductor at electrostatic equilibrium	Use zero field in the conducting material and constant potential throughout the conductor.
80	Capacitance	Divide stored charge magnitude by potential difference.
81	Parallel-plate capacitor	Relate capacitance to plate area, separation and permittivity in the ideal model.
82	Dielectric	A material that increases capacitance when inserted between plates in the standard model.
83	Electric current	Find charge crossing a section per unit time.
84	Resistance	Relate potential difference and current at the operating point.
85	Ohmic conductor	Use a constant resistance when current is proportional to voltage under fixed physical conditions.
86	Series circuit	Use the same current through components on one unbranched path.
87	Parallel circuit	Use the same potential difference across components sharing both endpoints.
88	Junction rule	Set total current entering a junction equal to total current leaving.
89	Loop rule	Sum signed potential changes to zero around a closed loop in the usual circuit model.
90	Electric power	Calculate the energy transfer rate using current and potential difference.
91	Magnetic force	Use the charge’s motion relative to the field and account for the charge sign.
92	Right-hand rule	Use the relevant rule to assign the direction of a cross product, field or induced response.
93	Magnetic flux	For a uniform field through a flat surface, multiply the normal field component by area.
94	Electromagnetic induction	Relate changing magnetic flux to an induced emf.
95	Lenz’s law	Choose the induced current direction that opposes the change in magnetic flux.
96	Fluid at rest	Use the hydrostatic pressure relation and buoyancy instead of a flow model.
97	Vector component	Project the vector onto the named coordinate axis with the correct sign.
98	Sign convention	State which direction is positive and use it consistently.
99	Scale drawing	Use the requested scale when converting between arrow length and vector magnitude.
100	Ranking task	Order the listed cases and show equal rankings where warranted.
101	Translate a representation	Preserve the physical relationships when switching between words, equations, diagrams and graphs.
102	Linearise data	Choose transformed axes that yield a straight-line relationship for the proposed model.
103	Qualitative prediction	State how the outcome changes and give a physical reason.
104	Quantitative translation	Use the mathematical relationship to connect a numerical result with a qualitative claim.
105	Experimental design and analysis	Give a repeatable method, then explain how its measurements test the relationship.
106	Mathematical routine	Build the algebra from a relevant principle and show how it answers the prompt.
107	Hypothesis	State a testable prediction about a relationship.
108	Research question	Specify the focused question that the investigation will answer.
109	Independent variable	Identify what the investigator changes deliberately.
110	Dependent variable	Identify the measured outcome of the investigation.
111	Controlled variable	Identify a factor kept constant to help isolate the tested relationship.
112	Control group	Use the baseline comparison to interpret the treatment effect.
113	Experimental design	Use the stated groups, conditions and measurements to judge the experiment.
114	Sample size	Check how many observations, individuals or trials contribute to the result.
115	Representative sample	Check whether the selected cases reflect the population of interest.
116	Raw data	Use the measurements as originally collected.
117	Processed data	Use values calculated, combined or transformed from the original readings.
118	Outlier	Identify an observation unusually far from the general pattern.
119	Uncertainty	State or interpret the estimated doubt associated with a measurement or value.
120	Error bars	Read their meaning from the figure legend before interpreting them.
121	Repeatability	Consider agreement when the same method is repeated under the same conditions.
122	Reproducibility	Consider whether results agree when the method is repeated under changed conditions.
123	Validity	Consider whether the evidence or method answers the intended question.
124	Reliability	Consider whether a result or method gives consistent findings.
125	Confounding factor	Identify a factor that could contribute to the apparent relationship.
126	Operational definition	Use the measurable rule the study gives for the concept.
127	Correlation	Describe how variables vary together within the data.
128	Causation	Explain how one factor produces a change in another when evidence supports it.
129	Trend	The broad direction or pattern over a range.
130	Pattern	A regularity visible across observations or examples.
131	Scatterplot	Describe form, direction, strength and unusual points when relevant.
132	Line of best fit	Draw a line representing the overall pattern of plotted data.
133	Interpolate	Estimate within the range covered by the data.
134	Extrapolate	Estimate outside the observed range using an assumed pattern.
135	Read the axes	Identify the quantities, units and intervals on a graph before using a value.
136	Gradient from a graph	Calculate change in the vertical quantity per change in the horizontal quantity.
137	Area under a graph	Use the area only where the graph’s quantities make it the requested accumulated value.
138	Baseline measurement	Use the reading taken before the stated intervention or change.
139	Identify the reference group	Find the comparison used to isolate the change attributed to the intervention.
140	Explain a limitation	Identify the assumption or data issue that restricts the conclusion.
141	Keep the comparison fair	Compare quantities on the same stated basis and units.
142	Control treatment	Use the treatment intended to provide a reference comparison.
143	Residual	Subtract the predicted response from the observed response.
144	Significant figures	Give the requested number of meaningful digits.
145	Decimal places	Count the required digits to the right of the decimal point.
146	Dimensional analysis	Track units through the calculation to see whether the result has the requested dimension.
147	Order of magnitude	Estimate the relevant power-of-ten scale.
148	Calculate the percentage change	Divide the change by the starting value and multiply by 100.
149	Rate of change	Find the change in one quantity per unit change in another.
150	Unit rate	Calculate the amount corresponding to one unit of the other quantity.
151	Parameter	Use the fixed or adjustable quantity that defines a family of cases.
152	Model	Use a simplified mathematical or conceptual representation to address the task.
153	Table	Information arranged in rows and columns.
154	Graph	A visual display of data or a mathematical relationship.
155	Diagram	A drawing showing features, structure or relationships.
156	Scale	The intervals or measurement relationship used in a display.
157	Unit	The standard attached to a measurement, such as minutes or metres.
158	Unit conversion	Use a conversion factor to change the units while keeping the quantity the same.
159	Interpret the slope	Give the predicted change in response per one unit increase in the explanatory variable.
160	Interpret the intercept	Explain the predicted response at zero if zero makes sense in context.
161	Exact value	Leave the answer in a form that preserves its full value.
162	Give units	Attach the required measurement unit to the final result.
163	Find the exact value	Retain radicals, fractions, logarithms or π in exact form where appropriate.
164	Set up an equation	Translate the given conditions into a mathematical relationship.
165	Check the solution	Substitute the result into the original equation to verify it.
166	In terms of	Use the specified quantity or symbol in the final expression.
167	Solve	Find the values that satisfy the equation or inequality.
168	Substitute	Replace a variable with the given value or expression.
169	Round	Adjust a number to the requested precision using the next digit.
170	Coordinate	Give the position using the specified ordered values.
171	Closed interval	Include both endpoints when the interval is closed.
172	Open interval	Exclude both endpoints when the interval is open at both ends.
173	Range of values	Find all possible outputs under the stated restrictions.
174	Initial condition	Use the given input and output to select a particular solution.
175	Direct relationship	As one quantity increases, the other increases under the stated conditions.
176	Inverse relationship	As one quantity increases, the other decreases under the stated conditions.
177	Initial value	Find the starting quantity, often the output at input zero.
178	Final value	The value at the stated end point.
179	Signed change	Subtract the initial value from the final value and retain the sign.
180	Relative change	Divide the difference by the initial value when that baseline is meaningful.
181	Order of operations	Apply operations in the sequence indicated by grouping and precedence.
182	Ratio	Compare two quantities by division in the order specified.
183	Proportional reasoning	Use the way quantities scale to connect two cases.
184	Reference value	A comparison value against which the result is interpreted.
185	Domain	Give the set of allowed input values in the context.

Evidence and other exam wording

No.	Instruction or term	Meaning or action
186	Contrast	Show how the items differ on a shared point of comparison.
187	Infer	Use clues to reach a conclusion the material implies.
188	Predict	Use available evidence to say what is likely to happen.
189	Suggest	Offer a plausible answer suited to the information given.
190	Assess	Judge the extent, value or strength of something using evidence.
191	Discuss	Develop a structured response that considers the relevant issues.
192	Distinguish	Give the feature that lets the reader tell two things apart.
193	Support	Supply evidence that helps establish the claim.
194	Illustrate	Make an idea clear with a relevant example or diagram.
195	Demonstrate	Show how a fact, process or result can be established.
196	Arrange	Put items into the order or grouping requested.
197	Sequence	Put stages into a meaningful order.
198	Classify	Assign each item to a category using the stated rule.
199	Order	Sort items by the criterion given in the prompt.
200	Omit	Leave out the indicated item or detail.

What the AP Physics C: Electricity and Magnetism exam requires

College Board lists the regular 2027 exam for May 5. The exam is hybrid digital. Answer multiple-choice items in Bluebook and read the free-response prompts there. Handwrite the free responses in the supplied booklet.

Exam component	Format and weighting
I · Multiple choice	42 questions in 85 minutes, worth 50%. Expect standalone items and sets that use shared information.
II · Free response	4 questions in 95 minutes, worth 50%. Tasks cover mathematical routines, translation between representations, experimental design and analysis, and translation between qualitative and quantitative descriptions.
Calculator policy	Both sections allow approved four-function, scientific or graphing calculators. Bluebook provides scientific and graphing Desmos calculators.

Use the May 2027 timing when building a mock exam. In graph and experiment tasks, match the diagram or measurement plan to the particular relationship named in the prompt.

AP is a U.S.-based programme taken domestically and internationally. Confirm local reporting time and registration with your school or test centre. Practise with the official materials for your course and exam year.

Read the task before choosing a method

Gauss’s law gives net flux through a closed surface. To extract field magnitude easily from it, explain how symmetry simplifies the integral. For induction, describe the change in flux and then determine the sign or current direction.

Worked examples for common exam instructions

Use symmetry to derive a field

Prompt. Find the electric field at distance r outside an isolated spherically symmetric charge distribution with total charge Q.

Answer. A concentric spherical surface has the same field magnitude everywhere and a radial field. Gauss’s law gives Eᵣ(4πr²) = Q/ε₀. Thus Eᵣ = Q/(4πε₀r²), with its sign giving the radial direction.

Differentiate potential

Prompt. In one dimension, V(x) = 6x² in SI units. Find Eₓ at x = 2 m.

Answer. Eₓ = −dV/dx = −12x. At 2 m it is −24 V/m, in the negative x direction.

Determine the direction of induced current

Prompt. A magnetic field into the page increases through a stationary conducting loop. Which way does induced current circulate as viewed from the front?

Answer. The induced field points out of the page to oppose the increase into the page. The right-hand rule gives counterclockwise current.

Design a test for the RC time constant

Prompt. Describe a way to estimate the time constant during capacitor discharge.

Answer. Measure capacitor voltage at known times after discharge begins. Plot ln(V/V₀) against time while voltage remains measurable and positive. The slope of the ideal straight line is −1/RC, so its negative reciprocal estimates RC.

Use the Fencing Method to build an answer

Start with a small, accurate response. Add the detail that fixes it to the question, then add the reason that connects them. Test the explanation on a new case.

Start. The induced current is counterclockwise.

Add context. The magnetic flux into the page is increasing.

Add reasoning. The induced current creates a field out of the page, so the right-hand rule gives counterclockwise circulation.

Transfer. Try a field into the page that is decreasing, and explain which direction reverses.

Practise with the 200 terms

Choose one calculation, one graph task and one explanation. Mark where the response identifies the quantity or relationship, provides the requested representation and explains the result. Change one condition and try again.

Identify what stays fixed

Try it. A charged ideal capacitor is disconnected before a dielectric is inserted. What happens to capacitance and voltage?

Check. Capacitance increases. With no path for charge transfer, charge remains fixed, so voltage Q/C decreases.

Frequently asked questions

What should I show when a prompt says justify?

Give the relevant principle or evidence and connect it to the conclusion. For a direction or sign, state the convention that makes the direction or sign meaningful. Check the scoring guidelines for the specific released question.

Official sources and next reading

College Board AP Physics C: Electricity and Magnetism exam information and released questions · AP calculator policy · 2027 AP exam schedule

Top 200 Vocabulary Word List for AP Physics C: Electricity and Magnetism | Must Know Words for Common Examination Instructions