SAT Subject Physics Practice Question 363: Answer and Explanation

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Question: 363

59.

The diagram above shows a proton at point B between two electrons at points A and C.The distance from point B to point C is twice the distance from point B to point A. The force the proton experiences at point B is

A. two times stronger from the electron at A.
B. three times stronger from the electron at A.
C. four times stronger from the electron at A.
D. the same from both electrons.
E. It is not possible to determine the force the proton experiences from the information provided.

Correct Answer: C

Explanation:

The correct answer is (C). The force exerted by a charged particle on another charged particle increases as the inverse of the square of the distance between them. Particle A, which has the same magnitude of charge as particle C, is half the distance from particle B as it is from particle C. Consequently, particle A exerts four times the charge on particle B as particle C does.

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