Question

Electric potential energy (U) of two point charges is

Answer 1

Correct option ⇒ (b) 

Electric potential energy of two points charges is $\frac{1}{4 \pi e_{0}} \frac{q_{1q_{2}}}{r}$  

Refers to the attachment 

For calculating the electrostatic potential energy of a system,two point charges q₁ and q₂ appears at two different points. separated by distance r₁ and r₂ respectively. 

Consider two point charges 

$U = q_{2}V_{1}(r)$
Where the $V_{1}(r) = kq_{1} /r$

Then , electric potential of two charge system is :-

$U = k \frac{q_{1}q_{2}}{r}$
Where $k = 1/4 \pi e_{0}$

Hence, if the point charges having same sign , then the positive work is done on the particle. To bring it from infinity.
If the point charges having opposite sign , then the negative work is done on the particle.To bring it from infinity.

Hope it Helps :-)

Answer 2

Electric potential energy (U) of two point charges is