Two balls of the same radius and weight are suspended on threads so that their surface are in contact. A charge of `q_(0) = 4 xx 10^(-7)C` is given to the balls which makes them repel each other and diverge to an angle of `60°`. Find the mass of the balls if the distance of balls from the point of suspension to the centre of ball is 20cm. Find the density of the material of the balls if the angle of divergence becomes `54°` when the balls are immersed in kerosene of density `800kg m^(-3)` dielectric constant ofkerosene is `epsilon_(r) = 2 [1.592g, 255 K//g m^(3)]`