$A$ light bulb is rated at $200 \text{ W}$ for a $220 \text{ V}$ supply. Find the resistance of the bulb. (in $\Omega$)

$A$ $12 \text{ HP}$ motor has to be operated $8 \text{ hours/day}$. How much will it cost at the rate of $50 \text{ paisa/kWh}$ in $10$ days? (in $Rs.$)

$n$ identical bulbs,each designed to consume power $P$ at a certain voltage source,are connected in series across the same source. The total power consumed by them is:

An electric kettle takes $4\, A$ current at $220\, V$. How much time will it take to boil $1\, kg$ of water from room temperature $20\, ^\circ C$? The temperature of boiling water is $100\, ^\circ C$. (Assume specific heat of water $c = 4200\, J/kg\, ^\circ C$)

If a $2\, kW$ boiler is used everyday for $1$ hour, then the electrical energy consumed by the boiler in thirty days is .......... $units$.

$A$ battery with $EMF$ $E$ and internal resistance $r$ is connected across a resistance $R$. The power consumption in $R$ will be maximum when: