The length of potentiometer wire is $600\mathrm{ }\mathrm{c}\mathrm{m}$ and a current of $\mathrm{40 }\mathrm{m}\mathrm{A}$ is flowing in it. When a cell of emf $\mathrm{2 }\mathrm{V}$ and internal resistance $10\mathrm{ }\mathrm{\Omega }$ is balanced on this potentiometer the balance length is found to be $500\mathrm{ }\mathrm{c}\mathrm{m}$ . The resistance of potentiometer wire will be