Charge & Coulomb’s Law
6 questionsKey ideaF = kq₁q₂/r². Like charges repel, and the force follows an inverse square law.
Common mistakeForgetting to square r, or thinking the larger charge feels the larger force (the forces are equal and opposite).
AP Physics 2 · Unit 10
Electric Force, Field, and Potential practice quiz
Covers: Coulomb’s law, fields, potential and capacitors. Quiz one topic at a time or take the whole unit.
- 23 questions
- 4 topics
- 3 FRQs
- Hints and explanations
Topics in this unit
The idea each topic turns on, and the mistake students make most often.
Electric Field
5 questionsKey ideaE = F/q. It points away from positive charges and toward negative ones, and fields from several charges add as vectors.
Common mistakeThinking the field depends on the test charge, or adding field magnitudes without directions.
Electric Potential & Energy
8 questionsKey ideaV = kq/r is a scalar, and ΔU = qΔV. Positive charges move toward lower V on their own.
Common mistakeAdding potentials as vectors, or forgetting the sign of the charge in ΔU = qΔV.
Capacitors
4 questionsKey ideaC = κε₀A/d and Q = CV. The energy stored is ½CV².
Common mistakeThinking C depends on the charge or voltage, or forgetting whether the battery is connected when the plates move.
Try a sample question
This is one of the 23 questions in the Unit 10 quiz.
Charge & Coulomb’s Law
A negatively charged rod is held near a neutral metal sphere without touching it. The sphere is briefly grounded, then the ground is removed, and then the rod is taken away. What is the sphere’s final charge?
- APositive
- BNegative
- CNeutral
- DIt depends on the size of the sphere
Show hint
Which way do the sphere’s electrons move when the negative rod is near? When the sphere is grounded, where can some of them go?
Show the answer and explanation
Answer: A. Positive
The rod repels electrons in the sphere. Grounding lets some of those electrons escape to the ground. With the ground removed first, the sphere is left with fewer electrons than protons, so it is positive. This is charging by induction.
Free-response practice
AP-style FRQs for this unit. Students score themselves point by point against a rubric and see a full solution.