In the fourth arm S of a post office box has a wire of length of 1 m and corss-sectional area of $1 \times 10^{-6} \mathrm{~m}^{2}$ is connected Now, the galvanometer gives zero deflection when 102 plug from arm Q, $1000 \Omega$ plug from arm P and $2025 \Omega$ plug from arm R are removed from the box. Determine the specific resistance.