Let a toatal chargem 2Q be dustrucuted in a sphere of radius , with the charge density given by ρ ( r ) = k r ρ(r)=kr, where r r is the distance from the centre. Two charges A A and B B, of − Q −Q each, are placed on diametrically opposite points, at equal distance a a, from the centre. If A A and B B do not experience any forces, then (a) a = 8 − 1 / 4 R a=8 −1/4 R (b) a = 3 R π 2 1 / 4 a= π2 1/4 3R ​ (c) a = 2 − 1 / 4 R a=2 −1/4 R (d) a = R 3 a= 3 ​ R ​

JEE - Electrostatic (Electrostatics Force and Field Strength)