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SAT® Subject Test in Physics

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Difficult

Work by E-Field to Move Charge

SATPHY-EKWLYE

Given the diagram below with positive and negative charges separated by the distance $d$, how much work (in Joules) would the electric field created by the pictured charges do on a separate $+1.0\ C$ charge in moving it from point $A$ to point $B$?

The blue charge is negative. The red charge is positive.

Answers are expressed in terms of $k$ (the coulomb constant) and given distances.

A

$ \frac { k }{ 2d } $

B

$ \frac { -k }{ 2d } $

C

$ \frac { k }{ 4d } $

D

$ \frac { -k }{ 4d } $

E

$ \frac { -k }{ d } $