Electric potential
Cambridge A-Level Physics (9702) · Unit 18: Electric fields · 7 flashcards
Electric potential is topic 18.5 in the Cambridge A-Level Physics (9702) syllabus , positioned in Unit 18 — Electric fields , alongside Electric fields and field lines, Uniform electric fields and Electric force between point charges. In one line: Electric potential at a point is the work done per unit positive charge in bringing a small test charge from infinity to that point. It is a scalar quantity, measured in volts (V).
Marked as A2 Level: examined at A Level in Paper 4 (A Level Structured Questions) and Paper 5 (Planning, Analysis and Evaluation). It is not tested on the AS-only papers (Papers 1, 2 and 3).
The deck below contains 7 flashcards — 1 definition, 4 key concepts and 2 calculations — covering the precise wording mark schemes reward. Use the definition card to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
Electric potential at a point
Electric potential at a point is the work done per unit positive charge in bringing a small test charge from infinity to that point. It is a scalar quantity, measured in volts (V).
What the Cambridge 9702 syllabus says
2025-2027 syllabus, in our words · A2 LevelWhat the syllabus expects you to be able to do in this topic, in plain English. For the exact wording, see the official syllabus (PDF).
- Define electric potential at a point: the work done on each unit of positive charge when a small test charge is moved from infinity to that point.
- Recall that the electric field strength at any point is the negative of the potential gradient there, and use this fact.
- Use V = Q/(4πε₀r) to find the electric potential at distance r in the field of a point charge.
- Use Eₚ = Qq/(4πε₀r) for two point charges, and understand how this electric potential energy follows from the idea of electric potential.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9702 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Define electric potential at a point.
Electric potential at a point is the work done per unit positive charge in bringing a small test charge from infinity to that point. It is a scalar quantity, measured in volts (V).
What is the relationship between electric field strength and electric potential gradient?
The electric field at a point is equal to the negative of the potential gradient at that point. Mathematically, E = -dV/dr, where E is electric field strength and dV/dr is the potential gradient.
State the formula for the electric potential due to a point charge Q at a distance r.
The electric potential (V) is given by V = Q / (4πε₀r), where Q is the charge, r is the distance from the charge, and ε₀ is the permittivity of free space.
Explain how the concept of electric potential leads to electric potential energy.
Electric potential defines the potential energy per unit charge at a location. Multiplying the electric potential (V) at a point by the charge (q) placed at that point gives the electric potential energy (EP): EP = qV.
State the formula for the electric potential energy of two point charges, Q and q, separated by a distance r.
The electric potential energy (EP) is given by EP = Qq / (4πε₀r), where Q and q are the charges, r is the distance between them, and ε₀ is the permittivity of free space.
Describe the sign convention for electric potential energy.
If the charges are of the same sign (both positive or both negative), the electric potential energy is positive, representing repulsive forces. If the charges are of opposite signs, the electric potential energy is negative, representing attractive forces.
How does electric potential change as you move closer to a positive charge?
Electric potential increases as you move closer to a positive charge. This is because work must be done by an external force to bring a positive test charge closer to another positive charge against the repulsive electric field.
Review the material
Read full revision notes on Electric potential — definitions, equations, common mistakes, and exam tips.
Read NotesMore topics in Unit 18 — Electric fields
Electric potential sits alongside these A-Level Physics decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Electric potential deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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