Physics

Problem

Four identical point charges

+q

are fixed at the four corners of a square of side

a

. A test charge

+q

is placed exactly at the centre of the square. What is the magnitude of the net electrostatic force acting on the central charge? a)

4k q^{2}/a^{2}

2\sqrt{2}\,k q^{2}/a^{2}

0

2k q^{2}/a^{2}