Find out the points on the line joining two charges `+q` and `-3q` (kept at a distance of `1.0` m), where electric potential is zero.

Explanation

Let P be the point on the axis either to the left or to the right of charge `+q` at a distance r, where potential is zero.

Hence, `V_(p)=(q)/(4pi epsilon_(0)r)-(3q)/(4pi epsilo_(0)(1+r))=0`
Solving this, we get
`r=0.5m`
Further, `V_(p)=(q)/(4piepsilon_(0)r)-(3q)/(4pi epsilon_(0)(1-r))=0`
which gives, `r=0.25` m
Thus, the potential will be zero at point P on the axis which is either `0.5` m to the left or `0.25` m to the right of charge `+q`.