PHYSICS · Multi-part · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
Two identical positive point charges, each of magnitude Q=3.0μC, are fixed to the ground at points separated by a horizontal distance 2d=0.60m. The midpoint of the line joining the charges is taken as the origin, and the upward vertical direction is the y-axis. A small bead of mass m=1.2×10−5kg carries a positive charge q whose magnitude is to be determined.
The bead is released from rest at a point located a vertical distance y=h above the origin on the y-axis. Assume g=9.8ms−2 and neglect air resistance.
(a) Show analytically that for any point on the y-axis the horizontal components of the electric forces exerted on the bead by the two fixed charges cancel.
(b) Using the result from part (a), derive an expression for h such that the bead can remain in static equilibrium at that height. Your expression should be in terms of Q, q, d, m, g, and fundamental constants.
(c) For q=+1.0μC, calculate the numerical value of h.