Charge q_1 = -8.5 nC is located at the coordinate system origin, while charge q_
ID: 1540342 • Letter: C
Question
Charge q_1 = -8.5 nC is located at the coordinate system origin, while charge q_2 = 1.42 nC is located at (a, 0), where a = 1.2 m. The point P has coordinates (a, b), where b = 0.55 m. A third charge q_3 = 3.5 nC will be placed later. Find the electric potential V_P at point P, in volts. Assume the potential is zero at infinity. V_P = How much work W, in joules, would you have to do to bring the third charge, q_3, from very far away to the point P? What is the total potential energy U, in joules, of the final configuration of three charges?Explanation / Answer
Given q1 = -8.5nc..(0,0).. q2 =1.42nc..(1.2, 0) ..q3 = 3.5nc..(1.2,0.55)..r1 =1.2m ..r2 =root of(1.2-0)2 + (0.55 -0)2 = 1.32m...1)ptential at p = kq/r1 + kq/r2 =9×109(-8.5/1.2+1.42/1.32)×10-9 = -54.09V....2work W = Vq -54.09×3.5×10-9 = -189.31×10-9J...3).. potential V = K (q1q2/r1 +q2q3/r2 + q3q1/r3) = 9×109(-8.5×1.42/1.2 +1.42×3.5/0.55+ (3.5×-8.5/1.32) ×10-9 =-212.02v