$A$ galvanometer of resistance $G$ is connected in a circuit. Now,a resistance $R$ is connected in series with the galvanometer. To keep the main current in the circuit unchanged,the resistance $S$ to be put in parallel with the series combination of $G$ and $R$ is:

$A$ battery of $emf$ $10\,V$ is connected to resistances as shown in the figure. The potential difference between $A$ and $B$,$(V_A - V_B)$ is ................ $V$.

In the circuit shown,$R_1$ is increased. What happens to the reading of the voltmeter (ideal)?

$A$ thermocouple of resistance $1.6\,\Omega$ is connected in series with a galvanometer of $8\,\Omega$ resistance. The thermocouple develops an e.m.f. of $10\,\mu V$ per degree temperature difference between two junctions. When one junction is kept at $0\,^{\circ}C$ and the other in a molten metal,the galvanometer reads $8\,mV$. The temperature of the molten metal,when e.m.f. varies linearly with temperature difference,will be ............ $^{\circ}C$.

Find the potential difference between $a$ and $b$,as shown in the below circuit. (in $V$)

$A$ $d.c.$ main supply of $e.m.f. \, 220 \, V$ is connected across a storage battery of $e.m.f. \, 200 \, V$ through a resistance of $1 \, \Omega$. The battery terminals are connected to an external resistance $'R'$. The minimum value of $'R'$ so that a current passes through the battery to charge it is ............... $\Omega$.