Current Electricity

Two wires '\(\mathrm{A}\)' and '\(\mathrm{B}\)' of equal length are connected in left and right gap respectively of meter bridge, null point is obtained at \(40 \mathrm{~cm}\), from the left end. Diameters of the wires '\(A\)' and '\(B\)' are in the ratio \(3: 1\) respectively, the ratio of specific resistance of 'A' to that of 'B' is