Physics

Problem

Four identical point charges

+q

are kept at the corners of a square of side

a

. The electric potential energy of the system is

U

. If the side of the square is increased to

2a

without changing the charges, the new potential energy is a)

\dfrac{U}{4}

\dfrac{U}{\sqrt 2}

\dfrac{U}{2}

\dfrac{U}{2\sqrt 2}