Unformatted text preview: positive V and –q gives rise to negative V. Scalar quantity U is the electric potential energy of a pair of point charges q 1 and q 2 separated by a distance r. q 1 and q 2 can carry + or – sign in this equation. The pair would have no electric potential energy if they are infinitely apart (r = ∞). If one of them is a negative charge and r is finite, the pair has a negative electrical potential energy. Moving one of them to infinity would require work input equal to the original U in joules. Why? Since U f = 0 and U i is negative, ∆ U = U f U i is positive in this case. Thus you can see work input is required to increase the electrical potential energy....
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This note was uploaded on 08/29/2010 for the course PHY 2049 taught by Professor Criss during the Fall '08 term at University of South Florida.
 Fall '08
 CRISS
 Physics, Charge, Force

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