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

$1\,\text{unit} =$ ...... electric energy.

$A$ constant potential difference is applied to the ends of a graphite rod, whose resistance decreases with a rise in temperature. The rod can be $(1)$ covered with asbestos or $(2)$ left open to the atmosphere. Answer for the steady state.

The voltage of clouds is $4 \times 10^6 \, V$ with respect to the ground. In a lightning strike lasting $100 \, ms$,a charge of $4 \, C$ is delivered to the ground. The power of the lightning strike is

$A$ hot electric iron has a resistance of $80\,\Omega$ and is used on a $200\,V$ source. The electrical energy spent,if it is used for two hours,will be ........... $Wh$.

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 $c = 4200\, J/kg\, ^\circ C$)