$A$ current source drives a current in a coil of resistance $R_1$ for a time $t$. The same source drives current in another coil of resistance $R_2$ for the same time. If the heat generated is the same,find the internal resistance of the source.

The potential difference between the points $P$ and $Q$ is nearly: (in $\,V$)

$A$ cell has an emf of $2 \, V$ and an internal resistance of $0.1 \, \Omega$. It is connected to an external resistance of $3.9 \, \Omega$. The terminal voltage across the cell will be: (in $V$)

In the given figure-$1$,the resistance of the shown voltmeter is variable. The variation of its reading with respect to its resistance is shown in figure-$2$. The value of $R$ is ............... $\Omega$.

In the circuit shown below,the current that flows from $a$ to $b$ when the switch $S$ is closed is ............... $A$.

An electrical circuit consists of ten $100 \,\Omega$ resistors. Out of these $10$ resistors,a group of $n_1$ resistors are connected in parallel and another group of $n_2$ resistors are separately connected in parallel. These two groups are then connected in series and this combination is connected to a voltage source of $100 \,V$. If the net current through the circuit is $2.5 \,A$,the values of $n_1$ and $n_2$ are: