Name the commercial unit of electrical energy. Convert it into joule. What is the other name of the commercial unit ?
The $V-I$ graphs for two resistors of the same material and the same radii with lengths $L_{1}$ and $L_{2}$ are shown below. If $L_{1}>L_{2}$, state with reason, which of these graphs represents voltage-current change for $L_{1}$.
$1\;kWh =\ldots\ldots$ $joule$
An electric iron draws a current of $0.5\, A$ when the voltage is $200$ volt. Calculate the amount of electric charge flowing through it in one hour.
$(a)$ Derive an expression to find the equivalent resistance of three resistors connected in series. Also, draw the schematic diagram of the circuit.
$(b)$ Find the equivalent resistance of the following circuit