AP Physics C: Electricity & Magnetism 8.2 A Describe the Behavior of a System Using Conservation of Charge Questions

Describe conservation of electric charge in an isolated system while charge moves between objects or regions during an interaction.

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

[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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AP Physics C: Electricity & Magnetism 8.2 A Describe the Behavior of a System Using Conservation of Charge Questions question 1