A point charge of +4.0 μC is fixed at x = 0 on a frictionless insulating rail that…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A point charge of +4.0 μC is fixed at x = 0 on a frictionless insulating rail that lies along the x-axis. A second point charge of unknown value Q is fixed at x = 0.30 m. A field sensor that does not disturb the existing charges is moved along the rail. At the location x = 0.18 m the sensor records zero electric field.
(1) Determine the magnitude and sign of Q.
(2) Find the coordinate of any other point on the x-axis where the electric field is zero.
(3) Explain why, for the sign of Q obtained in part (a), there is or is not a point between the two charges where the net electric field could be zero.