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Point Charges and Electric Fields

Please show all work and diagrams plus equations used to solve problem. Thanks!

Two point particles, with charges of q1 and q1 are placed a distance r apart. The electric field is zero at a point P between the particles on the line segment connecting them. We conclude that: (answer C - why)

a) q1 and q2 must have the same magnitude and sign
b) P must be midway between the particles.
c) q1 and q2 must have the same sign but may have different magnitudes.
d) q1 and q2 must have equal magnitudes and opposite signs.
e) q1 and q2 must have opposite signs and may have different magnitudes.

Two point particles, 1 with charge +8*10^-9C and the other with charge -2*10^-9C, are separated by 4m. The electric field in N-C midway between them is:

(Answers = 22.5 - WHY?)

Solution Preview

F= q^2/d^2 F net = Q1Q3/d12^2 + Q2Q3/d12^2 where d12 and d13 are the distances to point P
if q1 and q2 are opposite a charge Q3 will be attracted to q1 and repulsed by q2 or vice versa with the net force never being zero between the Q3 and the other charges.

If q1 and q2 are of the same charge then Q3 can either be of opposite charge and attracted to both q1 and q2 and at ...

Solution Summary

The solution provides detailed explanations and calculations for understanding the point where an electric field if zero between two point particles.