$A$ battery of $6$ cells,each with an $e.m.f.$ of $2\,V$ and an internal resistance of $0.5\,\Omega$,is being charged by a $220\,V$ $D.C.$ mains using an external resistor of $10\,\Omega$. What is the charging current in $A$?

In order to determine the $e.m.f.$ of a storage battery,it was connected in series with a standard cell in a certain circuit,and a current $I_1$ was obtained. When the battery is connected to the same circuit opposite to the standard cell,a current $I_2$ flows in the external circuit from the positive pole of the storage battery. What is the $e.m.f.$ $\varepsilon_1$ of the storage battery? The $e.m.f.$ of the standard cell is $\varepsilon_2$.

An ammeter $A$ of finite resistance and a resistor $R$ are joined in series to an ideal cell $C$. $A$ potentiometer $P$ is joined in parallel to $R$. The ammeter reading is $I_0$ and the potentiometer reading is $V_0$. $P$ is now replaced by a voltmeter of finite resistance. The ammeter reading now is $I$ and the voltmeter reading is $V$.

Assertion : An electric bulb becomes dim,when the electric heater in parallel circuit is switched on.
Reason : Dimness decreases after sometime.

An electric kettle has two coils. When one coil is switched on,the tea gets heated in $10 \, \text{min}$. When the other coil is switched on,the same amount of tea gets heated in $40 \, \text{min}$. If both coils are connected in parallel,how long will it take to heat the same amount of tea (in $, \text{min}$)?

$A$ battery consists of a variable number $n$ of identical cells (each having electromotive force $\varepsilon$ and internal resistance $r$) which are connected in series. The terminals of the battery are short-circuited and the current $I$ is measured. Which of the graphs shows the correct relationship between $I$ and $n\,?$