PHYSICS · Multi-part · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
Two point charges are fixed on the x-axis. A charge +3.0μC is located at x=0m, and a charge −12.0μC is located at x=0.40m. Assume the region is otherwise free of charges.
(a) Determine the coordinate(s) on the x-axis at which the net electric field due to the two charges is zero. Identify the interval(s) of the x-axis you considered and clearly state any points you exclude from your solution.
(b) Calculate the electric potential at the point you found in part (a), taking the potential to be zero at infinity. State both the magnitude and sign of the potential.
(c) A small positive test charge is placed at the location found in part (a) and then displaced infinitesimally along the x-axis. Explain whether the equilibrium at that point is stable, unstable, or neutral for motion confined to the x-axis. Justify your answer qualitatively without additional numerical calculations.