AP Physics 2 Study Guide: 2027 Exam, Seven Units, and Practice Strategy

AP Physics 2: Algebra-Based asks you to explain systems that are often invisible: thermal energy moving between objects, electric fields around charges, current in a circuit, magnetic forces, light forming an image, and the behavior of photons and matter. The most effective preparation is not a long list of equations. It is a habit of identifying the system, drawing a useful representation, choosing a physical principle, and checking whether the result makes sense. This guide follows the current College Board framework for the 2026–27 school year and shows how to turn its seven units into a workable study plan.

A crucial update comes first. Some older AP Physics 2 resources still start with fluids and number the course as Units 1–7. The current College Board course framework lists AP Physics 2 as Units 9–15: thermodynamics; electric force, field, and potential; circuits; magnetism and electromagnetism; geometric optics; waves, sound, and physical optics; and modern physics. Fluids now belongs to the current AP Physics 1 sequence. This page follows the current AP Physics 2 organization. Use an older lesson only after checking that its concept and notation still match the current course and exam description.

What to know about the May 2027 exam

The College Board exam page schedules AP Physics 2 for Thursday, May 6, 2027, Session 1. Your school's AP coordinator provides the exact reporting time and location; do not assume a universal clock time because start-time rules vary by location. The exam is hybrid digital: multiple-choice questions and free-response prompts appear in Bluebook, while students handwrite free-response answers in a paper booklet. Practicing only on a keyboard therefore misses an important part of exam readiness: writing compact, legible explanations and calculations by hand under time pressure.

Starting with the 2027 exam, Section I has 42 multiple-choice questions in 85 minutes and accounts for half the exam score. Section II has four free-response questions in 95 minutes and accounts for the other half. The four free-response types are mathematical routines, translation between representations, experimental design and analysis, and qualitative/quantitative translation. These labels describe what you must do, not four isolated content chapters. A circuits question might ask you to construct a graph; an optics question might ask you to compare two experimental arrangements. The exam also supplies reference information, and calculators are permitted under College Board policy. Verify the currently allowed calculator and reference-sheet details before exam day rather than relying on an old prep book.

Because the course connects representations, study each idea in at least three forms. For an electric field, for example, explain the direction in words, sketch field vectors or equipotentials, and use an equation when a numerical prediction is needed. If one form contradicts another, that is an opportunity to diagnose a misunderstanding before the exam. The current released questions and scoring materials are especially useful for learning what a complete justification looks like. Note that College Board warns older released questions may not completely align with the current course after the 2024–25 physics revisions, so check each problem against the current framework.

Start with the physics habits that transfer across units

Before substituting numbers, name the system and its boundaries. A system might be a gas in a cylinder, two interacting charges, a resistor network, or a ray of light crossing a lens. The choice determines which transfers are external and which are internal. In thermodynamics, heat and work cross a system boundary; internal energy belongs to the system. In circuits, charge moving through a junction does not vanish. In optics, a ray diagram is a model of light paths, not a picture of energy collecting at one point. A clear system statement prevents many wrong-equation errors.

Next, build a representation that exposes the relevant principle. Draw a circuit with all junctions, mark current directions as assumptions, sketch an energy bar chart, draw normal lines at optical boundaries, or label field direction before calculating a force. A wrong arrow is less damaging when you explicitly define a direction and keep your sign convention consistent. Units provide a second check: electric potential is measured in joules per coulomb, while electric field is newtons per coulomb. They are related but not interchangeable. If a computation gives meters for a voltage, the algebra or the chosen relationship is wrong.

Finally, explain the limiting case. If resistance increases while ideal battery voltage stays fixed, total current should fall. If the object is moved very far from a converging lens, the image should approach the focal plane. If temperature rises at fixed volume for an ideal gas, pressure should rise. These short checks make formula use meaningful and help you reject attractive multiple-choice distractors. If you need a bridge from earlier topics, review the AP Physics 1 course hub for conservation, energy, and representation habits that carry into Physics 2.

Unit 9: Thermodynamics

Thermodynamics connects a microscopic picture of particles with measurable pressure, volume, temperature, and energy transfer. The ideal gas law, PV = nRT, is a model for a gas under specified assumptions. It does not say that pressure, volume, and temperature can all change independently. If the quantity of gas stays fixed and a rigid container is heated, volume stays constant while pressure rises with absolute temperature. Use kelvin in gas-law ratios: a change from 300 K to 600 K doubles temperature, while a change from 30 °C to 60 °C does not. Begin each problem by listing what is fixed, what changes, and which state variables are being compared.

The first law of thermodynamics is an energy-accounting statement. Choose and state your sign convention for work, then apply it consistently. A gas can gain internal energy when energy enters as heat; its internal energy may also change when work is done on it. If the gas expands while heating, some transferred energy may leave as work, so the temperature response cannot be inferred from heat input alone. On a pressure–volume graph, work by the gas is related to the area under the process curve. A graph is thus not decorative: it lets you compare processes with different paths between the same endpoints.

Learn to distinguish isothermal, isobaric, and isochoric processes by what stays constant, then check whether a statement refers to a process or a state. Temperature is a state property; heat and work describe transfers along a path. For an ideal gas, internal energy depends on temperature, but different paths between the same states can involve different heat and work. A useful practice question is to compare two ways of reaching the same final pressure and volume. Explain why their internal-energy changes agree while their work terms can differ. That reasoning is more durable than memorizing one formula per process.

Thermal equilibrium and entropy are also conceptual. When objects at different temperatures are placed in thermal contact, energy transfers until a common temperature is reached if the composite system is isolated. The final temperature depends on each object's thermal capacity, not simply the arithmetic average. Entropy helps describe the direction of spontaneous processes and the number of accessible microscopic arrangements; it is not a synonym for 'mess.' In a lab, make measurements, identify heat loss to the surroundings, and discuss how that loss would bias an inferred specific heat. The unit is an excellent place to practice modeling assumptions explicitly.

Unit 10: Electric force, field, and potential

Electric charge is conserved, but charges can move from one object to another. Coulomb's law describes the magnitude of the interaction between idealized point charges and shows an inverse-square dependence on separation. Doubling separation makes the force one quarter as large, provided the charges and medium are otherwise unchanged. The sign of charge determines whether the force is attractive or repulsive. When multiple charges act, add forces as vectors rather than adding their magnitudes blindly. Draw directions first, because a positive and a negative source charge can produce field contributions that reinforce in one region and oppose in another.

The electric field at a location is defined by the force per unit positive test charge there. It is a property of the source configuration, not of the test charge used to probe it. A positive charge accelerates initially in the field direction; a negative charge experiences a force in the opposite direction. If you are asked whether the field is zero at a point, compare the vector contributions from all source charges. A zero net field does not necessarily mean zero electric potential, because potential is a scalar sum. Conversely, a location where potential is defined as zero need not have zero field.

Potential difference measures energy change per charge and is often the more useful quantity for energy reasoning. As a positive charge moves in the direction of an electrostatic field, its electric potential energy decreases; a negative charge must be considered separately because U = qV. Equipotential lines cross electric-field lines at right angles. On a field or potential map, closer equipotential lines usually indicate a stronger field magnitude in that region. Do not infer field direction from 'higher numbers' without checking whether the values are potentials and remembering that the field points toward decreasing potential.

A strong study exercise is to compare two parallel plates. Sketch a nearly uniform field between the plates, mark the potential change across the separation, and predict the motion of both positive and negative test charges. Then change plate spacing while holding either voltage or charge fixed. The answers are not identical because the controlled quantity matters. This exercise links diagrams, energy, and algebra. For additional practice, use the site's electric charge lesson as a concept review while following the current College Board Unit 10 terminology on this page.

Unit 11: Electric circuits

Circuits become easier once you separate three ideas: charge conservation, energy transfer, and material response. Current is charge flow per time. At a junction, the total current entering equals the total current leaving, because charge does not accumulate in a steady-state ideal circuit. Voltage is an energy-per-charge difference supplied or consumed by components. Resistance describes how a component relates voltage and current under specified conditions; the simple V = IR relationship is appropriate for an ohmic resistor, not automatically for every device. A battery establishes potential difference; it does not 'use up' current as charge traverses the circuit.

In series, the same current passes through each component because there is only one path. The potential drops across ideal resistors sum to the source voltage. In parallel, branches share the same potential difference while current divides according to branch resistance. Consider an ideal 12 V battery connected to two 6 Ω resistors. In series, equivalent resistance is 12 Ω and current is 1 A. In parallel, equivalent resistance is 3 Ω and total current is 4 A; each 6 Ω branch carries 2 A. These results are not conflicting: connecting the same components differently changes the load seen by the source.

Power is the rate of energy transfer. For a resistor, P = IV, with alternative forms obtained by combining it with Ohm's law where appropriate. Do not memorize 'higher resistance means higher power' without naming what is held constant. At fixed voltage, P = V²/R, so higher resistance means lower power. At fixed current, P = I²R, so higher resistance means higher power. The apparent contradiction vanishes when the conditions are explicit. On exam questions, annotate the controlled variable beside the equation before comparing bulbs, heaters, or resistors.

For capacitor circuits, understand qualitatively how charge, potential difference, and stored energy change as a capacitor charges or discharges, and whether a battery remains connected. A statement about 'constant voltage' may be true for a capacitor attached to an ideal battery but false after disconnection. In experiments, distinguish ideal schematic assumptions from real components, wires, meters, and source internal resistance. If measured values differ from an ideal prediction, diagnose which assumption could account for the direction of the discrepancy. The site's circuit overview can supply extra examples; use the current official Unit 11 ordering as your exam map.

Unit 12: Magnetism and electromagnetism

A magnetic field exerts a force on a moving charged particle and on a current-carrying wire. Direction is central: the magnetic force is perpendicular to the particle's velocity and the magnetic field. For a positive charge, apply the right-hand rule; reverse the force direction for a negative charge. A stationary charge in a static magnetic field experiences no magnetic force. A particle moving exactly parallel to the field also has zero magnetic force from that field, even though it is moving. These are useful limiting cases for checking a diagram.

Because a magnetic force is perpendicular to instantaneous velocity, it changes direction of motion without directly changing the particle's kinetic energy. Uniform circular motion can result when velocity is perpendicular to a uniform field, but real trajectories depend on the initial velocity components and field region. When a problem combines electric and magnetic fields, analyze each force separately before adding them. A velocity selector, for example, can use opposing electric and magnetic forces to let particles of one speed travel undeflected; it is not because either field is absent.

Electromagnetic induction links changing magnetic flux to an induced emf. Ask what changes: field strength, loop area, orientation, or some combination. Lenz's law says the induced effect opposes the change in flux, not necessarily the existing field itself. A loop approaching a region with increasing outward flux responds differently from a loop leaving that region. Sketch the before-and-after flux and then determine the induced current direction. This sequence is safer than trying to recall a memorized arrow diagram. In a generator or transformer discussion, connect changing flux to energy transfer and avoid suggesting that induction creates energy from nothing.

Unit 13: Geometric optics

Geometric optics models light as rays that travel straight within a uniform medium and change direction at a boundary. Reflection uses equal angles measured from the normal. Refraction depends on the medium's refractive index and the change in wave speed. When light enters a medium with a higher refractive index, its ray bends toward the normal; when it enters a lower-index medium, it bends away. Frequency stays the same across the boundary, while speed and wavelength change. Always draw the normal line before measuring angles: many wrong answers come from measuring from the surface instead.

A ray diagram for a mirror or lens is a geometric argument about where rays converge or appear to originate. A real image can be projected onto a screen; a virtual image cannot be formed on a screen by placing it at the apparent image location. For a converging lens, an object beyond the focal point generally forms a real image on the other side; an object inside the focal length forms a virtual upright image. Use at least two principal rays, label object and image distances, and compare the diagram with any thin-lens equation result. Algebra without a sketch makes sign mistakes hard to catch.

Total internal reflection requires light to travel from a higher-index medium toward a lower-index medium and strike the interface above the critical angle. It cannot occur for the reverse direction. In a lab, a measured focal length can vary because of alignment, thick-lens effects, or difficulty judging the sharpest image. Explain which uncertainty dominates and how repeated measurements might reduce random variation. Optics questions often combine prediction and experimental critique, so practice both rather than treating the unit as ray drawing alone.

Unit 14: Waves, sound, and physical optics

A wave carries energy through a medium or space without transporting the medium's material along the entire route. Distinguish amplitude, wavelength, frequency, period, and speed; each answers a different question. For a wave moving at speed v, v = fλ. If a sound wave enters a different medium and its speed changes, its frequency remains fixed by the source while its wavelength changes. If the source frequency changes within the same medium, wavelength changes inversely when speed stays approximately constant. An annotated graph or snapshot makes these relationships easier to see than an isolated equation.

Superposition means overlapping wave displacements add. Constructive interference occurs when contributions reinforce; destructive interference occurs when they oppose. In a double-slit or diffraction setting, explain which path difference corresponds to a bright or dark region before applying a formula. Do not say that two waves are 'destroyed' in a permanent sense at a dark fringe: energy is redistributed across the interference pattern. For standing waves, nodes and antinodes encode boundary conditions. A string fixed at both ends and an air column with one open end have different allowed patterns, so first identify the physical boundaries.

Sound introduces intensity, resonance, and the Doppler effect. A higher pitch corresponds to higher frequency, while loudness is linked to intensity and perception rather than frequency. In the Doppler effect, distinguish motion of source, observer, and medium, and test whether the observed frequency should rise when they approach. In optical interference, path difference and wavelength play similar roles, but light need not behave exactly like sound in every medium. A useful study method is to place two diagrams side by side—one for mechanical waves and one for light—and note the shared superposition principle alongside the different physical mechanisms.

Unit 15: Modern physics

Modern physics asks where classical models are insufficient. In the photoelectric effect, light transfers energy in packets called photons. Photon energy is proportional to frequency, so light below a metal's threshold frequency cannot eject electrons merely by increasing intensity in the simple photoelectric model. Above the threshold, increasing frequency raises the maximum electron kinetic energy, while increasing intensity generally increases the number of emitted electrons if other conditions are fixed. This is a useful example of separating two independent controls rather than applying a blanket 'more light means more energy per electron' claim.

Atomic energy levels are quantized. An atom absorbs or emits a photon whose energy matches the difference between two allowed levels. When an electron moves to a lower level, a photon can be emitted; to move to a higher level, the atom must gain energy. A spectral line is evidence of a particular energy difference, not a continuous smear of every possible photon energy. Practice translating among an energy-level diagram, a wavelength or frequency, and a verbal description of an emission or absorption event. Check the direction of the transition before calculating.

Some questions also ask you to reason about wave-particle behavior or nuclear processes. Keep the model's domain clear: a wave model explains interference, while a photon model is essential for threshold behavior in the photoelectric effect. Conservation of energy and charge remain useful even when the microscopic model changes. If you encounter a formula in a prep source that is absent from the current reference information, learn what physical relationship it expresses and confirm whether it belongs to the current course; do not assume that every chapter of a general college-physics book is an AP Physics 2 requirement.

How to answer the four free-response styles

For a mathematical-routines question, show the physical relationship before substitution, preserve units, and explain why the expression applies. A numerical answer without a valid pathway can conceal an accidental match. For translation between representations, move deliberately from one form to another: table to graph, diagram to equation, or graph to explanation. Name what the slope, area, intercept, or direction represents. If a graph is qualitative, label axes and show the correct trend; decorative precision is less useful than a physically consistent shape.

For experimental design and analysis, write a procedure another student could perform. Identify the independent variable, what will be measured, what will be controlled, and how measurements test the proposed relationship. If the claim is that current varies inversely with resistance at fixed voltage, specify how voltage is kept fixed, where meters are placed, what resistance values are used, and what graph or calculation will evaluate the claim. Include a plausible source of uncertainty and, when asked, predict the direction of its effect. 'Human error' alone is too vague to be informative.

For qualitative/quantitative translation, connect the numerical model to a causal explanation. Suppose a circuit's total resistance doubles while ideal source voltage remains constant. State that total current halves, show the relevant relationship, and explain that the potential difference per unit charge is unchanged while less charge passes a point per second. If a result seems surprising, revisit assumptions such as ideal source, negligible wire resistance, or constant temperature. Write in complete but concise sentences; graders need the reasoning that connects a principle to the conclusion.

Across all four types, read the verbs. 'Calculate' calls for a value with units; 'derive' calls for a symbolic relationship from stated premises; 'justify' calls for evidence or a physical principle; 'compare' calls for an explicit relation between cases. Many lost points arise when a student gives a true fact but not the requested inference. After practicing, compare your work with the official scoring guidelines and sample responses. Highlight the missing logical step, not only the incorrect final number, and redo that step a day later without looking at the solution.

An eight-week study plan

In weeks 1 and 2, diagnose your starting point and review thermodynamics and electric fields. Take a short mixed quiz, categorize errors by concept, representation, algebra, or reading, and create a one-page error log. Work one laboratory-style explanation each week. Review prerequisites—energy conservation, forces, and graphs—from AP Physics 1 only when a specific gap blocks the Physics 2 problem. This keeps prerequisite review targeted rather than allowing it to consume the study window.

In weeks 3 and 4, focus on circuits, magnetism, and electromagnetism. Draw every circuit and field setup before calculating. Practice junction and loop reasoning, then move to induction scenarios where a changing flux must be identified. Mix questions from earlier units at the end of each session so recall is spaced. At least once, explain a solution aloud to another person or write it as if teaching a classmate. If you cannot explain why an arrow points in a particular direction, revisit the physical rule before doing more arithmetic.

In weeks 5 and 6, study geometric optics, waves, and modern physics. Sketch ray diagrams and wave patterns, then check them against equations and limiting cases. Work short sets in which the same principle appears in different contexts—for example, energy transfer in thermal systems, circuits, and photons. Compare what stays conserved and what is being transferred. Use official released free-response material selectively, checking that each task still matches the current framework. Schedule one timed handwritten response each week to build speed and legibility.

In week 7, simulate the exam format: a timed 85-minute multiple-choice section and a timed 95-minute set of four free-response types when suitable current-style practice is available. Review by error category rather than score alone. In week 8, revisit the most frequent two or three weaknesses, rehearse the Bluebook preview and paper-booklet workflow, check calculator and reference-sheet rules, and protect sleep. Cramming a new topic the night before is usually less useful than practicing accurate setup and clear reasoning on familiar ideas. If your course schedule differs, keep the sequence of diagnosis, focused repair, mixed practice, and timed simulation even if the week labels move.

Common mistakes worth correcting early

Do not treat a formula sheet as a substitute for a model. The sheet may show a relationship, but it will not tell you which system is isolated, whether a circuit component is in series, which direction a force points, or whether an image is real. Avoid carrying an old unit map into the 2027 exam: fluids resources can still teach useful physics, but the current AP Physics 2 framework begins with thermodynamics. Do not confuse heat with temperature, electric field with potential, current with energy, or photon intensity with photon energy. These pairs are related, yet each quantity has a distinct definition and unit.

When a practice answer is wrong, write a correction that names the exact faulty assumption. 'I forgot the formula' is less useful than 'I treated parallel branches as if they had equal current instead of equal potential difference.' Keep diagrams and laboratory notes; College Board notes that lab experience is part of the course and that colleges may ask to see laboratory materials when evaluating credit. Above all, practice explaining why a physical prediction follows from evidence. That habit improves multiple-choice elimination, free-response clarity, and your ability to recognize when an apparently plausible answer violates conservation or a limiting case.

Official resources and next steps

Use the current AP Physics 2 course page as the source of truth for units and science practices, the exam page for the May 2027 format, the 2027 exam schedule for date confirmation, and official released questions for scoring-guideline practice. Your teacher's AP Classroom materials may provide more current aligned tasks. Treat this guide as a route through the subject, not a replacement for your course, labs, or the official course and exam description.