In a potentiometer of 10 wires, the balance point is obtained on the 6th wire. To shift the balance point to 8th wire, we should

The length of germanium rod is $$0.925 \mathrm{~cm}$$ and its area of cross-section is $$1 \mathrm{~mm}^2$$. If for germanium $$n_i=2.5 \times 10^{19} \mathrm{~m}^{-3}, \propto_n=0.19 \mathrm{~m}^2 / \mathrm{V}-\mathrm{s}, \propto_e=0.39 \mathrm{~m}^2 / \mathrm{V}$$-s, then the resistance of the rod is

A cell of emf 1.8 V gives a current of 17 A when directly connected to an ammeter of resistance 0.06 $$\Omega$$. Internal resistance of the cell is