$A$ battery with an internal resistance of $4\,\Omega$ is connected to a circuit as shown in the figure. For the circuit to receive maximum power,the value of $R$ should be ..... $\Omega$.

$A$ set of $n$ equal resistors,each of value $R$,are connected in series to a battery of emf $E$ and internal resistance $R$. The current drawn is $I$. Now,the $n$ resistors are connected in parallel to the same battery. The current drawn from the battery becomes $10I$. The value of $n$ is:

$A$ 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 how much time will one litre of ${H_2}$ be collected by a $5\, A$ current? (Given: $Z = 1 \times {10^{ - 8}}\,kg/C$ and density of ${H_2} = 0.09\,kg/{m^3}$)

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

In the circuit shown in the figure below,which of the following statements is incorrect?