Find the $emf$ $(E)$ of the cell in $V$ required to light the bulb rated $4.5 \, W, 1.5 \, V$ fully,as shown in the circuit.

In the given circuit,an ideal voltmeter connected across the $10\,\Omega$ resistance reads $2\,V$. The internal resistance $r$ of each cell is ................... $\Omega$.

Three light bulbs of $40\, W$,$60\, W$,and $100\, W$ are connected in series with a $220\, V$ source. Which one of the bulbs will glow brightest?

The figure shows a network of resistors and a battery. If $1\,A$ current flows through the branch $CF$,then find the $emf$ $E$ of the battery. (in $,V$)

$A$ storage battery has an $e.m.f.$ of $15\, V$ and an internal resistance of $0.05\, \Omega$. Its terminal voltage when it is delivering $10\, A$ of current is ............... $V$.

In the circuit shown,the current through $R_2$ is zero. If $R_4 = 2\,\Omega$ and $R_3 = 4\,\Omega$,the current through $R_3$ will be ................. $A$.