Infinite number of cells having $emf$ and internal resistance $\left( {E,r} \right)$, $\left( {\frac{E}{n},\frac{r}{n}} \right)$, $\left( {\frac{E}{{{n^2}}},\frac{r}{{{n^2}}}} \right)$, $\left( {\frac{E}{{{n^3}}},\frac{r}{{{n^3}}}} \right)$..... are connected in series in same manner across an external resistance of $\frac{{nr}}{{n + 1}}$ . Current flowing through the external resistor is
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The charge flowing through a resistance $R$ varies with time according to $Q = at -bt^2.$ The total heat produced in $R$ is : (assume that direction of current not reversed)
A potentiometer consists of a wire of length $4\, m$ and resistance $10 \,\Omega$. It is connected to cell of $emf$ $2\, V$. The potential difference per unit length of the wire will be ............ $V/m$
The potential difference across $8\, ohm$ resistance is $48\, volt$ as shown in the figure. The value of potential difference across $X$ and $Y$ points will be ............. $volt$
$12$ cells each having the same emf are connected in series and are kept in a closed box. Some of the cells are wrongly connected. This battery is connected in series with an ammeter and two cells identical with each other and also identical with the previous cells. The current is $3\, A$ when the external cells aid this battery and is $2\,A$ when the cells oppose the battery. How many cells in the battery are wrongly connected :-
In the circuit shown below, the switch $S$ is connected to position $P$ for a long time so that the charge on the capacitor becomes $q _1 \mu C$. Then $S$ is switched to position $Q$. After a long time, the charge on the capacitor is $q _2 \mu C$.
The equivalent resistance between the points $P$ and $Q$ in the network given here is equal to ................ $\Omega$ (given $r = \frac{3}{2}\Omega $)
The voltage of clouds is $4 \times 10^6\,volt$ with respect to round. In a lighteing strike lasting $100\,m\,sec$, a charge of $4\,coulombs$ is delivered to the ground. The power of lightening strike is