Question

A point charge a of charge + 4c and another point charge b of charge-1pc are placed in air at a distance 1 metre apart. Then the distance of the point on the line joining the charges and from the charge b, where the resultant electric field is zero, is (in metre): (a) 0.5 (b) 1.5 ( 2 (d) 1

Answer 1

let distance from b  is x  , so from a is 1-x

kq*(-1)/x^2 + kq*4/(1-x)^2 = 0

1-x = -2x

x = -1

- sign means this is not between them , but away from one

so answer is 1m away from A