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A -3.0 nC charge is on the x-axis at x = -9 cm and a +4.0 nC charge is on the x-axis at x = 15 cm. At what point or points on the y-axis is the electric potential zero. y = _____ cm

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The electric potential is a scalar that is given by:

V = k * q / r

If the net potential at y = 2 cm on the y-axis is zero, then this point (assuming that P) would be zero.

V_net = V1 + V2 = 0

k * q1 / r1 + k * q2 / r2 = 0

k * q2 / r2 = -k * q1 / r1

q2 / r2 = -q1 / r1

Assumption: q1 = -3.0 nC&q2 = 4.0 nC

r1 = distance between P and q1 = sqrt ((-9.0-0.0)2 + (0-d)2) = sqrt (81 + d2)

r2 = distance between P and q2 = sqrt ((19-0),2 +(0-d),2) = sqrt (361 + d,2)

And so it is

4.0 / square foot (361 + d ^ 2) = 3.0 / square foot (81 + d ^ 2)

Square sides

16.0 / (361+ d.2) = 9.0 / (81/ + d.2)

16 * 81 + 16* d 2 = 9.0* 361 + 9.0* d 2

d 2 = [9.0* 361-16 *81] /7.0= 279

d = square feet ([279]) = pm 16.7cm

The potential at that point will be null

y = 16.7 cm & y = -16.7 cm