
Four point charges and are fixed at the points, and respectively on the A particle of mass and of charge moves along the direction. Its speed at is Find the least value of for which the particle will cross the origin. Find also the kinetic energy of the particle at the origin. Assume that space is gravity-free. Given:
Important Questions on Electrostatics




A positive charge is distributed in a spherical region with charge density for (where is a positive constant and is the distance from centre). Find out electric potential and electric field at following locations.
(a) At a distance from centre inside the sphere.
(b) At a distance r from centre outside the sphere.



A ball of radius carries a positive charge whose volume density depends only on the separation from the ball’s centre as , where is a constant. Assuming the permittivity of the ball and the environment to be equal to unity, find :
(i) The magnitude of the electric field strength as a function of the distance r both inside and outside the ball;
(ii) The maximum intensity and the corresponding distance .
