Question

1. Calculate the distance of separation between 2 electron (in a vacuum) for which the electric force between them is equal to the gravitation on one of them at the earth surface. Take the mass of the electron =9.1*10-³¹ kg, Charge of electron = 1.6*10-19 C

Answer 1

The balance of forces condition

F_gravity=F_electric

So

mg=k q^2/r^2

The distance

r=√((kq^2)/mg)=√((9×〖10〗^9×(1.6×〖10〗^(-19) )^2)/(9.1×〖10〗^- ³¹×9.8))=5.1 m