Question

Calculate the potential energy of a charge +6nC placed at 0.07m from a charge +76 x10^-6C. If the same charge(+6nC) is now at 0.07m from a charge -88 x10^-6C, find its new potential energy.   

Answer 1

Now we know that

Potential energy

$U=\frac{kq_1 q_2}{r}$

$$U=\frac{9\times10^9\times6\times10^{-9}\times76\times10^{-6}}{0.07}=0.05862J$$

$$U=-\frac{9\times10^9\times6\times10^{-9}\times88\times10^{-6}}{0.07}=-0.0678J$$