The electric potential for an electric field directed parallel to X-axis is shown in the figure. Choose the correct plot of electric field strength.
Two charges, each equal to $$-$$q are kept at ($$-$$a, 0) and (a, 0). A charge q is placed at the origin. If q is given a small displacement along y direction, the force acting on q is proportional to
A neutral conducting solid sphere of radius R has two spherical cavities of radius a and b as shown in the figure. Centre to centre distance between two cavities is c. qa and qb charges are placed at the centres of cavities respectively. The force between qa and qb is
Consider two concentric conducting sphere of radii R and 2R respectively. The inner sphere is given a charge +Q. The other sphere is grounded. The potential at $$r = {{3R} \over 2}$$ is