Define surface density of electric charge.
Two large conducting spheres carrying charges `Q_(1) and Q_(2)` are brought close to each other. Is the magnitude of the electrostatice force between them exactly given by `(Q_(1)Q_(2))/(4 piin_(0)r^(2))`, where r is the distance between their centres?
Or, Define dielectric constant . Two charges `pm 20 xx 10^(-6)`C, placed 2 mm apart from an electric dipole. Determine the electric field at a point 10 cm away from the centre of the dipole on its perpendicular bisector. Given,`(1)/(4 pi in_(0)) = 9 xx 10^(9)" "N cdot m^(2)cdot C^(-2)`.