The figure shows a network of resistances and cells in which the point $A$ is earthed. The point which has the least potential is

$A$ 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 ..... $\Omega$.

In the adjoining circuit diagram,each resistance is of $10 \ \Omega$. The current in the arm $AD$ will be

Three resistances $A, B$ and $C$ having values $3R, 6R$ and $R$ respectively form a network as shown. When a potential difference is applied across the network,the thermal powers dissipated by $A, B$ and $C$ are in the ratio:

Two resistances of $400 \Omega$ and $800 \Omega$ are connected in series with a $6 \text{ V}$ battery of negligible internal resistance. $A$ voltmeter of resistance $10000 \Omega$ is used to measure the potential difference across the $400 \Omega$ resistor. The error in the measurement of potential difference in volts is approximately:

The total current supplied to the following circuit by the battery is (in $ A$)