In the given circuit,the reading of the ideal voltmeter is $\frac{E}{2}$. Find the internal resistance $r$ of the cell in $\Omega$.

In the circuit given below,if the bulb is to glow with maximum intensity,the value of $R$ is (neglect internal resistance of the cell) (in $\Omega$)

The charge flowing through a resistor $R$ varies with time $t$ as $Q = 3t - 6t^2$. The heat produced in $R$ until the current in it becomes zero is:

In the circuit shown below,the resistances are given in $\Omega$ and the battery is assumed ideal with an emf equal to $3\,V$. The voltage across the resistance $R_4$ is ................. $V$.

An electric iron draws $5\, A$,a $TV$ set draws $3\, A$,and a refrigerator draws $2\, A$ from a $220\, V$ main line. The three appliances are connected in parallel. If all three are operating at the same time,the fuse used should be of ............. $A$. (in $, A$)

$A$ car has a fresh storage battery of emf $12 \, V$ and internal resistance $2 \times 10^{-2} \, \Omega$. If the starter motor draws a current of $80 \, A$, then the terminal voltage when the starter is $ON$ is: (in $V$)