Question

Two charges of magnitude `5 nC and -2 nC` are placed at points (2cm,0,0) and (x cm,0,0) in a region of space. Where there is no other external field. If the electrostatic potential energy of the system is `-0.5 muJ`. What is the value of x ?

Answer 1

Correct Answer - x = 4cm
`U = (1)/(4pi in_(0)) (q_(1) q_(2))/(r )`
`-5xx10^(-6) = (9xx10^(9)xx5xx10^(-9)xx(-2)xx10^(-9))/((x-2)xx10^(-2))`
`x - 2 = (9xx10^(9)xx5xx10^(-9)xx -2xx10^(-9))/(-0.5xx10^(-6)xx10^(-2))`
On solving, `x = 4cm`