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.
Field and potential rules, from your 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!
This tool splits the text you paste by rule and returns cards. It cannot compute a field or read a diagram, so it works on the rules you already wrote down.
Two midpoints, and they are the whole lesson
Between two equal and opposite charges the potential cancels to zero while the field adds up. Between two equal like charges the field cancels while the potential adds. Those two cases appear constantly because they prove you know which quantity is a vector and which is a number.
Sign is information for potential and a direction for field
Potential can be negative and that negative is part of the sum. A field cannot be negative in the same sense; it points somewhere. Dropping a minus sign in a potential calculation and dropping a direction in a field calculation are different mistakes with the same cause.
Charges move towards lower potential energy, not lower potential
A positive charge falls towards lower potential; a negative charge does the opposite, because energy is charge times potential and the sign flips. Stating the rule in terms of energy rather than potential makes it work for both signs, and questions include negative charges precisely to test it.
Equipotentials are a map you can read directly
They are perpendicular to field lines everywhere, and closely spaced lines mean a strong field. That makes a contour diagram readable without calculation: crowded means strong, and moving along a line costs no work. Questions supply these diagrams because reading them is faster than computing.
Path independence is why potential exists at all
Work between two points depends only on the difference in potential, not on the route taken. That is what allows a single number to be assigned to each location, and it is why energy methods work here for the same reason they work in mechanics.
What to photograph for Electric Force, Field and Potential
Diagrams with your sign conventions written out. Related: Unit 9, photo to quiz and pricing.
Sources used on this page
- College Board, AP Physics 2
- Electric field
- Electric potential
- Coulomb's law
- Electric potential energy
- 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
| Quantity | Type | How contributions combine |
|---|---|---|
| Electric force | Vector | Add with directions |
| Electric field | Vector | Add with directions |
| Electric potential | Scalar | Add with signs |
| Potential energy | Scalar | Add with signs |
| Between opposite charges | Midpoint | Potential zero, field large |
| Between like charges | Midpoint | Field zero, potential large |
What is AP Physics 2 Unit 10?
Electric Force, Field and Potential: Coulomb's law, the electric field, potential and potential energy, and equipotential diagrams.
Why do the two midpoint cases keep appearing?
Because they separate vectors from scalars. Opposite charges cancel in potential and add in field; like charges do the reverse.
Can potential be negative?
Yes, and the sign is part of the sum. A field is not negative in that sense; it has a direction instead.
Which way does a charge move?
Towards lower potential energy. A positive charge falls towards lower potential and a negative one towards higher, so state the rule in terms of energy.
How do I read an equipotential diagram?
Lines are perpendicular to the field, and closely spaced lines mean a strong field. Moving along a line costs no work.
Why does path independence matter?
Because it is what lets a single number be assigned to each point. Without it, potential could not be defined.
Last updated: 2026-08-15