Electric potentialAQA A-Level Physics: Flashcards
What these 12 flashcards ask
- Define absolute electric potential at a point.
- What is the potential at infinity?
- What is the unit of electric potential?
- Is electric potential a scalar or a vector?
- Give the equation for work done moving a charge through a potential difference.
- Why is no work done moving a charge along an equipotential?
- What shape are equipotentials around a point charge?
- What is the formula for the potential at distance r from a point charge Q?
- How does V vary with r for a point charge, compared with E?
- State the equation linking E and V.
- How can ΔV be found from an E–r graph?
- What does the negative sign in E = −ΔV/Δr show?
Exam questions on Electric potential
- A small sphere carries a charge of +6.0 nC, which may be treated as a point charge at its centre. The sphere is isolated in a vacuum (ε₀ = 8.85 × 10⁻¹² F m⁻¹).State what is meant by the absolute electric potential at a point in an electric field.2 marks
- Points A and B lie in the radial electric field of an isolated point charge of +3.0 nC in a vacuum. Point A is 0.20 m from the charge and point B is 0.50 m from it (ε₀ = 8.85 × 10⁻¹² F m⁻¹).Point C is also 0.20 m from the charge. Explain why no work is done on a charge moved from A to C.2 marks
- In a region of space the electric potential falls uniformly with distance along a straight line, from 800 V at one point to 200 V at a second point 0.30 m further along the line. The field in this region is uniform.Use E = −ΔV/Δr to calculate the magnitude of the electric field strength in this region, and state its direction relative to the change in potential.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).