How much work is required to separate two charges $7\mu C$ and $-2 \mu C$ placed $18 ext{ cm}$ apar

Question

How much work is required to separate two charges $7\mu C$ and $-2 \mu C$ placed $18	ext{ cm}$ apart infinitely away from each other?

Professor PC Thomas Classes · Answer

Work required to separate them to infinity is $W = U_{final} - U_{initial} = 0 - (-0.7	ext{ J}) = 0.7	ext{ J}$.