The current through a conductor is '$$\mathrm{a}$$' when the temperature is $$0^{\circ} \mathrm{C}$$. It is '$$\mathrm{b}$$' when the temperature is $$100^{\circ} \mathrm{C}$$. The current through the conductor at $$220^{\circ} \mathrm{C}$$ is

On increasing the temperature of a conductor, its resistance increases because

A galvanometer having a resistance of $$8 \Omega$$ is shunted by a wire of resistance $$2 \Omega$$. If the total current is $$1 \mathrm{~A}$$, the part of it passing through the shunt will be

Two cells with the same emf $$E$$ and different internal resistances $$r_1$$ and $$r_2$$ are connected in series to an external resistance $$R$$. If the potential difference across the first cell is zero then value of $$R$$.