Two point charges +10 q and -4 q are located at x =0 and x = L respectively. What is the location of a point on the x -axis from the origin, which the net electric field due to these two point charges is zero? ( r = required distance )

Step-by-step solution

Let ' Q ' be the point at a distance r from -4 q and ( L + r ) from 10 q . wherein net electric field is zero. aligned & E₁=E₂ & K(10 q) (L+r)^2 = K(4 q) r^2 aligned aligned & 10 ~L + r = 2 r & 5 2 ~L + r = 2 2 r = 2 r & 5 2 r =2( ~L + r ) & 5 2 r = 2 2 ( ~L + r ) & 5 r = 2 ~L + 2 r & 5 - 2 r = 2 ~L & r = 2 5 - 2 aligned If B is position of charge -4 q then point Q is r= 2 5 - 2 to the right of B