When a resistance of $9 \,\Omega$ is connected across the terminals of a battery,its potential difference decreases from $40 \, V$ to $30 \, V$. The internal resistance of the battery is ............... $\Omega$.

When a resistance $R_1$ is connected across a cell,the current is $I_1$ and if the resistance $R_1$ is replaced by $R_2$,the current is $I_2$. Then the internal resistance of the cell is

What will be the equivalent resistance between the two points $A$ and $D$ in the given circuit (in $Omega$)? (All resistors are $10 \ \Omega$ each.)

If power dissipated in the $9 \,\Omega$ resistor in the circuit shown is $36 \,W$,the potential difference across the $2 \,\Omega$ resistor is .......... $V$

For the circuit shown,the value of current at time $t=3.2 \, s$ will be ...... $A$. (Voltage distribution $V(t)$ is shown by Figure $1$ and the circuit is shown in Figure $2$)

The smallest temperature difference that can be measured with a combination of a thermocouple of thermo $e.m.f.$ $30\,\mu V$ per degree and a galvanometer of $50\,\Omega$ resistance,capable of measuring a minimum current of $3 \times 10^{-7} \, A$ is ............... $^\circ C$.