The tool below drills the geometry from your own notes.
WeSolve+ reads the whole document and writes the questions for you
Upload your PDF, photograph your notebook, or point the camera. WeSolve+ writes questions from that material, explains why each answer is right, reads the chapter back to you as a podcast, and remembers every item you missed until you own it.
The tool below is a small browser-only tool and it is not WeSolve+: paste a few lines and text rules turn them into cards on the spot. The real app, the one that uses AI, is behind the link above.
Unit 12 field rules, from your own notes
This is a browser-only tool, and that is all it isIt splits the text you paste by rule, and nothing else. WeSolve+ is a different thing entirely: it reads your whole PDF with AI, writes the reasoning behind every question, speaks the chapter back to you, and remembers what you missed so it can return it. Try the real app now, free!
What you paste is what gets carded. Fixed rules split the text and nothing outside it is known, which makes the paste itself the real decision.
The force is perpendicular to everything, and that is the content
A magnetic field pushes a moving charge sideways: perpendicular to the velocity and to the field at once, with magnitude qvB sine theta. Motion along the field feels nothing. Because the push is always sideways, the force does no work and speed survives, which questions test by asking what changed, direction, and what did not, energy.
Right hand rules are the unit's arithmetic, so drill them as one
Point fingers with the velocity, curl toward the field, and the thumb gives the force on positive charge; flip it for negative. Grip a wire with the thumb along current and fingers circle with the field. Every direction question in the unit is one of these two moves, and hesitation between them is where the marks leak.
Circular motion falls out when the field does the steering
A charge entering a uniform field at right angles turns in a circle: the sideways force plays centripetal, so qvB equals mv squared over r and the radius carries the momentum. Mass spectrometer prompts live here, heavier or faster particles sweep wider arcs, and the algebra is one line once the geometry is stated.
Induction begins with flux, so compute the flux first
Flux is field times loop area times the cosine between them, and only its change induces anything. Faraday's law sets the induced emf by the rate of that change: shrink the loop, strengthen the field or turn it, and the loop answers. Prompts that keep flux constant are testing whether you check before computing.
Lenz's law is bookkeeping with a direction, and it never flatters
The induced current flows to oppose the change that made it: flux growing into the page drives a counterclockwise fight, a magnet approaching a loop meets a mirror pole. Energy conservation is the reason, since a current that helped the change would amplify itself for free. Writing opposes the change, then the direction, is the two step answer.
What to photograph for Magnetism and Electromagnetism
Your field sketches and rule tables. Related: Unit 10, photo to quiz and pricing.
Sources used on this page
- College Board, AP Physics 2: Algebra-Based
- Magnetic field
- Lorentz force
- Electromagnetic induction
- Solenoid
- Active recall
- Spaced repetition
- Testing effect
- Forgetting curve
- Generation effect
- Judgment of learning
- Metacognition
- Desirable difficulty
- Distributed practice
- Formative assessment
- Flashcard
- Cloze test
- Multiple choice
- Test (assessment)
- Educational assessment
- Advanced Placement
- Curriculum
- Study skills
- Study guide
- Note-taking
- Overlearning
- Instructional scaffolding
- Item analysis
- Mastery learning
| Setup | The rule to use | The verdict |
|---|---|---|
| Charge moves across field | Palm rule for force | Sideways push, circle follows |
| Charge moves along field | Sine of zero | No force at all |
| Current in a wire | Grip rule | Field circles the wire |
| Two parallel currents | Field of one at the other | Same direction attracts |
| Magnet approaches a loop | Lenz's law | Loop shows a matching pole |
| Loop area shrinks in field | Faraday's law | Emf from the flux change rate |
What does AP Physics 2 Unit 12 cover?
Magnetic fields from magnets and currents, forces on moving charges and wires, flux, Faraday's law and Lenz's law.
Why does the magnetic force do no work?
It stays perpendicular to velocity, so it changes direction while leaving speed and kinetic energy untouched.
When does a moving charge feel no magnetic force?
When it moves along the field line: the force carries sine theta, and the angle's sine is zero.
What is magnetic flux?
Field strength times loop area times the cosine of the angle between field and the loop's normal. Only its change induces an emf.
How do I get the direction of an induced current?
Lenz's law: the current opposes the change in flux. State the change, then choose the direction whose field fights it.
Can I build questions from my own Unit 12 notes?
Yes. Upload the chapter as a PDF or photograph the pages, and every question comes from those pages rather than from the wider syllabus.
Last updated: 2026-08-15