SAT Subject Physics Practice Question 82: Answer and Explanation

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Question: 82

9.

9. How much work would the electric field (created by the stationary charge Q) perform as a charge q is moved from point B to A along the curved path shown?

(VA = 200 V, VB = 100 V, q = –0.05 C, length of line segment AB = 10 cm, length of curved path = 20 cm.)

A. 0 J
B. 5 J
C. 10 J
D. 15 J
E. 20 J

Correct Answer: B

Explanation:

9 B By definition, WE = –qV, which gives

WE = ‒q(VAVB) = ‒(‒0.05 C)(200 V ‒ 100 V) = 5 J

Notice that neither the length of the segment AB nor that of the curved path from A to B is relevant.

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