The figure below shows currents in a part of electric circuit. The current $I$ is

Two batteries of e.m.f. $4 \mathrm{V}$ and $8 \mathrm{V}$ with internal resistances $1 \mathrm{\Omega }$ and $2 \mathrm{\Omega }$ are connected in a circuit with a resistance of $9 \mathrm{\Omega }$ as shown in figure. The current and potential difference between the points $P$ and $Q$ are respectively

The magnitude and direction of the current in the circuit shown will be

Calculate potential difference between points $d$ and $b$ in the circuit.

In the given circuit diagram, a connecting wire of negligible resistance is joining the points $\mathrm{B}$ and $\mathrm{D}$, the current in the connecting wire is 

If the ammeter in the given circuit reads $2 \mathrm{A}$, the resistance $R$ is