Electric Charges, Fields, and Gauss’s Law unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1 Paper 2 Paper 3

Each paper is built from this unit’s 22 terms and is the same for everyone, so a teacher can assign “Unit 1, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.

Suggested time 34 min 31 points0/17 attempted

Charge on a conductor surface

Field of an infinite line of charge

Symmetry arguments to eliminate components

Superposition of fields

Field of a continuous charge distribution

Checking a field expression

Flux through a closed surface with no enclosed charge

Coulomb's law in vector form

Why symmetry is required for Gauss

Field on the axis of a charged ring

Gauss's law vs direct integration

Field inside a uniformly charged insulating sphere

Short answer 1. Define or explain: Field inside a conductor in electrostatic equilibrium

3 pts

Short answer 2. Define or explain: Electric flux

3 pts

Short answer 3. Define or explain: Charge densities

3 pts

Short answer 4. Define or explain: Electric field of a point charge

3 pts

Free response

7 pts

A solid insulating sphere of radius R has a uniform volume charge density ρ.

Use Gauss's Law to derive an expression for the magnitude of the electric field E(r) inside the sphere (r < R).

Derive an expression for the electric potential V(r) at the surface of the sphere, assuming V = 0 at infinity.

A proton (charge +e) is released from rest at the surface. Determine its kinetic energy when it reaches a distance 3R from the center.