Current through a wire is given by I=nevdA=nevdπR2 Here, n= number density of free charge carriers vd= drift speed of electrons R= radius of wire e= charge on an electron Here, for two wires A and B IA=IB (given) nA=nB (wires have same material) RA=2RB (given) so we have, IA=IB ⇒nevAπRA2=nevBπRB2 ⇒