Four point charges, each of + q , are rigidly fixed at the four corners of a square planar soap film of side ` a `. The surface tension of the soap film is γ The system of charges and planar film are in equilibrium, and a = k [ q 2 γ ] 1 / N , where ' k ' is a constant. Then N is: 3 9 4 2 be obtained by heating?