Quick answer: Electric potential is potential energy per unit charge, V = U/q, measured in volts. This AP Physics C test on electric potential has 8 questions worth 20 marks, to do in 45 minutes: meaning of potential, point charge and reading the graph. The mark scheme is on a separate page; free printable PDF.
Also, this test lasts 45 minutes and is marked out of 20. Show every step of calculations, quote answers with units, and write explanations in full sentences. Use k = 8.99 × 10⁹ N·m²/C² and e = 1.60 × 10⁻¹⁹ C.
Level: AP Physics C (Mechanics and E&M, calculus-based) · Curriculum: AP PC:E&M Unit 9
Question 1 Meaning of potential (2 marks)
Define electric potential and state what is meant by a potential difference of 12 V between two points.Question 2 Point charge (2 marks)
Calculate the potential 0.20 m from a −6.0 nC point charge.Question 3 Reading the graph (3 marks)
Moreover, the graph shows the potential along the x-axis.- Calculate the field for 0 < x < 0.30 m, with its direction. (2 marks)
- Also, explain what the graph shows about the field for 0.30 m < x < 0.50 m. (1 mark)
Question 4 Integrating a field (3 marks)
a field is E = (4.0 × 10³ V/m²)x in +x. Calculate V(0.10 m) − V(0).Question 5 Equipotentials (2 marks)
Moreover, explain why electric field lines cross equipotential surfaces at right angles.Question 6 Conducting sphere (3 marks)
A conducting sphere of radius 0.10 m carries +20 nC. Also, calculate the potential at (a) its surface and (b) its centre, and (c) state E at its centre.Question 7 Ring on its axis (3 marks)
A ring of radius 0.30 m carries 2.0 nC. Calculate the potential at the point on its axis 0.40 m from its centre, and explain why the answer needs no vectors.Question 8 Energy of a charge (2 marks)
Moreover, a proton is released from rest and moves through a potential difference of 500 V. Calculate its speed (m = 1.67 × 10⁻²⁷ kg).
