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(14%) Problem 5: Charge q,-7.5 nC is located at the coordinate system origin, wh

ID: 1656537 • Letter: #

Question

(14%) Problem 5: Charge q,-7.5 nC is located at the coordinate system origin, while charge q2--1.67 nC is located at (a, 0), where a = 0.65 m. The point P has coordinates (a, b), where b = 0.55 m. A third charge q,-17 nC will be placed later. y (a,b) qi 4 2 Otheexpertta.com - 33% Part (a) Find the electric potential P at point P, in volts. Assume the potential is zero at infinity. - 33% Part (b) How much work W in joules, would you have to do to bring the third charge, q3-from very far away to the point P? 33% Part (c) what is the total potential energy U, in joules, of the final configuration of three charges?

Explanation / Answer


(a)


r1 = sqrt(a^2+b^2) = sqrt(0.65^2+0.55^2) = 0.85 m


potential due to q1 = V1 = k*q1/r1 = 9*10^9*7.5*10^-9/0.85 = 79.4 V

potential due to q2 = V2 = k*q2/r = -9*10^9*1.67*10^-9/0.55 = -27.334 V


total potential Vp = V1 + V2

Vp = 79.4 - 27.33 = 52.07 V <<<------ANSWER


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part(b)

work = Vp*q3 = 52.07*17*10^-9 = 8.85*10^-7 J <<<--------ANSWER

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part (C)

total potential energy U = k*q1*q2/r12 + k*q2*Q3/r23 + k*q1*q3/r13


U = -9*10^9*7.5*10^-9*1.67*10^-9/0.65 - 9*10^9*1.67*10^-9*17*10^-9/0.55 + 9*10^9*7.5*10^-9*17*10^-9/0.85


U = 7.12*10^-7 J <<<--------ANSWER