Two identical batteries, each of $e.m.f.$ $2\,V$ and internal resistance $1.0\,\Omega$, are available to produce heat in an external resistance $R = 0.5\,\Omega$ by passing a current through it. The maximum Joulean power that can be developed across $R$ using these batteries is ............. $W$.

In the circuit shown,the potential difference between $A$ and $B$ is ............. $V$.

In the given diagram,an ideal voltmeter $V$ reads $1.45\,V$. Then the relation between $r_1$ and $r_2$ is:

When cells are connected in parallel,then

An electric eel generates an electric current using biological cells called electroplaques. The eel has a total of $5000$ electroplaques arranged in $100$ rows. This arrangement is shown in the figure. Each electroplaque has an $emf$ of $0.15\ V$ and an internal resistance of $0.25\ \Omega$. The water surrounding the eel completes the circuit between its head and tail. If the resistance of the water is $500\ \Omega$,the electric current generated by the eel in the water is .......... $A$.

Two batteries,one of e.m.f. $12 \text{ V}$ and internal resistance $2 \Omega$ and other of e.m.f. $6 \text{ V}$ and internal resistance $1 \Omega$,are connected as shown in the figure. What will be the reading of the voltmeter '$V$' (in $\text{ V}$)?