Electric Potential of a System of Two Point Charges
Two point Charges of `4muC` and `-2muC` are seprated by a distance of 1 m in air. Calculate at which point on the line joining the two charges is the electric potential zero.

Explanation

Let the electrostatic potential be zero at point P between the two charges separated by a distance x metre.

At point P, `V_(p)=V_(1)+V_(2)=0`
`(1)/(4pi epsilon_(0))*(q_(1))/(r_(1))+(1)/(4pi epsilon_(0))*(q_(2))/(r_(2))=0`
`(1)/(4pi epsilon_(0))*(4xx10^(-6))/(x)+(1)/(4piepsilon_(0))*((-2xx10^(-6)))/((1-x))=0`
or `(4xx10^(-6))/(x)=(2xx10^(-6))/((1-x))`
`4/x=(2)/((1-x))`
`2(1-x)=x`
`2=3x" or "x=(2)/(3)m`
`:.` Electrostatic potential is zero at a distance 2/3 m from Charge `4muC` between the two charges.