In the circuit shown in the figure, $E_1$ and $E_2$ are two ideal sources of unknown emfs. Currents are given. Potential difference appearing across the $6 \mathrm{\Omega }$ resistance is, $V_{\mathrm{A}}-V_{\mathrm{B}}=10 \mathrm{V}$.

$\left(\mathrm{I}\right)$ The current in the $4 \mathrm{\Omega }$ resistor between $C$ and $D$ is $5 \mathrm{A}$.

$\left(\mathrm{II}\right)$ The unknown emf $E_1$ is $36 \mathrm{V}$.

$\left(\mathrm{III}\right)$ The unknown emf $E_2$ is $54 \mathrm{V}$.

$\left(\mathrm{IV}\right)$ The resistance $R$ is equal to $9 \mathrm{\Omega }$.

Which of the above statements are correct?

Find the current in the branch $CD$ of the circuit.

In the circuit shown, the potential difference across $AB$ and the current in it, respectively, are

In the circuit shown, the value of $R$ (in $\mathrm{ohms}$) that will result in no current through the $30 \mathrm{V}$ battery is

The reading of the voltmeter is

The reading of ammeter (in $\mathrm{amperes}$) for the following circuit is

The reading of ammeter (in $\mathrm{amperes}$) for the following circuit is

Two cells of emf $10 \mathrm{V}$ and $15 \mathrm{V}$ are connected in parallel to each other between points $A$and $B$. The cell of emf $10 \mathrm{V}$ is ideal but the cell of emf $15 \mathrm{V}$ has an internal resistance $1 \mathrm{\Omega }$. The equivalent emf between $A$and $B$ is