$A$ $8 \Omega$ resistor is connected to a battery that has an internal resistance of $0.2 \Omega$. If the voltage across the battery (the terminal voltage) is $10 \ V$,then the emf of the battery is (in $V$)

Three identical bulbs are connected as shown in the figure. When switch $S$ is closed,the power consumed in bulb $B$ is $P$. What will be the power consumed by the same bulb when switch $S$ is opened?

$A$ current of $2\,A$ flows through a $2\,\Omega$ resistor when connected across a battery. The same battery supplies a current of $0.5\,A$ when connected across a $9\,\Omega$ resistor. The internal resistance of the battery is:

In the given circuit,the resistance of the voltmeter is $10,000\, \Omega$ and the resistance of the ammeter is $20\, \Omega$. The ammeter reading is $0.1\, \text{A}$. If the voltmeter reading is $12\, \text{V}$,then the value of $R$ is ............ $\Omega$.

The actual value of resistance $R$,shown in the figure is $30\,\Omega$. This is measured in an experiment as shown using the standard formula $R_{measured} = \frac{V}{I}$,where $V$ and $I$ are the readings of the voltmeter and ammeter,respectively. If the measured value of $R$ is $5\%$ less than the actual value,then the internal resistance of the voltmeter is ................. $\Omega$.

Two cells of $e.m.f.$ $E_1$ and $E_2$ and of negligible internal resistances are connected with two variable resistors as shown in the figure. When the galvanometer shows no deflection,the values of the resistances are $P$ and $Q$. What is the value of the ratio $E_2/E_1$?