The paths AA¢, AD and AB are obviously symmetrically placed in the
network Thus, the current in each must be the same, say, I Further,
at the corners A¢, B and D, the incoming current I must split equally
into the two outgoing branches In this manner, the current in all
the 12 edges of the cube are easily written down in terms of I, using
Kirchhoff’s first rule and the symmetry in the problem