$A$ household supply is $220 \, V$ with a fuse of $9 \, A$. What is the maximum number of $60 \, W$ bulbs that can be connected in parallel and operated simultaneously?

$A$ given quantity of water is boiled by an electric heater in $5 \text{ min}$. If the supply voltage of the heater is reduced to half,then the time taken to boil the same quantity of water will be . . . . . . $\text{min}$. (Assume the resistance of the heater remains constant.)

Two wires have resistances of $2 \ \Omega$ and $4 \ \Omega$ and are connected to the same voltage. The ratio of heat dissipated in the resistances is:

Define kilowatt hour and power.

The number of electrons moving per second through the filament of a lamp of $60 \text{ W}$ operating at $120 \text{ V}$ is nearly $(e = 1.6 \times 10^{-19} \text{ C})$

An electric bulb marked as $50 W - 200 V$ is connected across a $100 V$ supply. The present power of the bulb is (in $W$)