To measure the temperature coefficient of resistivity $$\alpha$$ of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25°C and resistance of the semiconductor arm is $$3 \text{ m}\Omega$$. Arm BC is cooled at a constant rate of $$2 \text{ °C s}^{-1}$$. If the galvanometer G shows no deflection after 10 s, then $$\alpha$$ is