If $10$ bulbs of $50\,W$ are used for $10$ hours a day,how many units of electricity will be consumed in a month ($30$ days)?

An electric heater rated $220 \,V$ and $550 \,W$ is connected to $AC$ mains. The current drawn by it is (in $\,A$)

$A$ circular wire has a current density $J = (2 \times 10^{10} \text{ A/m}^2) r^2$, where $r$ is the radial distance from the center and the wire radius is $2 \text{ mm}$. The potential difference applied across the wire is $50 \text{ V}$. How much energy (in Joules) is converted to thermal energy in $100 \text{ s}$ (in $\pi$)?

$n$ identical bulbs,each designed to draw a power $P$ from a certain voltage supply,are joined in series across that supply. The total power which they will draw is

Consider an electrical conductor connected across a potential difference $V$. Let $\Delta q$ be a small charge moving through it in time $\Delta t$. If $I$ is the electric current through it,
$I$. the kinetic energy of the charge increases by $I V \Delta t$.
$II$. the electric potential energy of the charge decreases by $I V \Delta t$.
$III$. the thermal energy of the conductor increases by $I V \Delta t$.
Choose the correct option.

In the figure shown,the power generated in $y$ is maximum when $y = 5\,\Omega$. Then $R$ is