What is the potential energy of this configuration?

Question

Consider two charges q1= 0.2 u C and q2 = 3 u C that are 0.5m away from each other. What is the potential energy of this configuration?

Answer 1

The formula for potential energy

E = kq₁q₂/r

= 8.988×10⁹ N⋅m²⋅C^-2 × 0.2 × 10^-6 C × 3 × 10^-6 C / 0.5 m

= 0.01 J

Note that the potential energy is positive, meaning that if nothing keeps the two

positive charges together then they will fly away from each other to infinity.