AP Physics C: Electricity & Magnetism 8.2 Conservation of Electric Charge and the Process of Charging Questions

Describe how electric charge is conserved while charge transfers between objects or regions through charging processes in an isolated system.

Exam points

predict induced charge separation and polarization in nearby conductors or insulators
track electron transfer and final net charge through grounding or contact sequences
apply charge conservation to leakage, redistribution, or inner and outer conductor surfaces

Covered syllabus points

8.2.A—Describe the behavior of a system using conservation of charge

[Maximum number: 1]

A very long nonconducting cylinder is surrounded by a thin concentric conducting cylindrical shell, as shown in the cutout view. A segment of length L of the inner cylinder has a net charge of +Q uniformly distributed throughout its volume. A segment of length L of the outer shell has a net charge of +4 Q. The radii of the inner cylinder and outer shell are R and 3 R, respectively, as shown in the cross-section view.

Determine the charge on the outer surface of the cylindrical shell within length L.

For correctly determining the charge on the outer surface of the shell 1 point

Example Response

\begin{aligned} & q_{\text {net }}=q_{\text {inner }}+q_{\text {outer }} \\ & q_{\text {outer }}=q_{\text {net }}-q_{\text {inner }} \\ & q_{\text {outer }}=+4 Q-(-Q) \\ & q_{\text {outer }}=+5 Q \end{aligned}

Scoring Note: A correct response may earn a point even if no work is shown.

Total for part (a)

1 point

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Covered syllabus points

Question 1