Question

Two particles each of mass M and carrying charge of magnitude q each are at some separation if they are in equilibrium under mutual electrostatic and gravitational forces of the order then q/m(in c/kg) is

Answer 1

repulsive electrostatic force: attractive gravitational force:
F1=kQ^2/r^2 F2=Gm^2/r^2

for equilibrium :F1=F2
kQ^2/r^2=Gm^2/r^2
=> Q/m = (6.6*10^-11/9*10^9)^1/2
=> Q/m=0.8*10^-10
Hence, ORDER OF Q/m=10^-10