Initial resistance , R = 4 Ω Resistance of a wire is given by R = ρLA . When the wire is doubled on itself, its length becomes halved (L/2) and area of cross-section becomes doubled (2 A). Therefore,          R  = ρL A     = ρ(L/2)(2A)     = 14ρLA    =14R     = 14×4 Ω     = 1Ω. is the new resistance of the wire.