Electric Potential 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.
Potential from a distribution
Potential energy of a charge configuration
Why field is the negative gradient
Field and potential can be independently zero
Field from a graph of V vs x
Potential from a graph of E vs x
Accelerating a charge through a potential difference
Electric potential of a point charge
Electron volt
Energy of assembling charges
Why potential is easier than field
Work and potential difference
Short answer 1. Define or explain: Potential inside a uniformly charged insulating sphere
3 ptsShort answer 2. Define or explain: Equipotential surfaces
3 ptsShort answer 3. Define or explain: Potential inside a conducting sphere
3 ptsShort answer 4. Define or explain: Relation between field and potential
3 ptsFree response
7 ptsThis course has no free-response prompt tagged to this unit, so one from elsewhere in the course is used. It is still worth writing — the skill transfers.
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.