How many units are consumed if a $100\,W$ electric bulb is kept $ON$ for $10$ hours?

Two bulbs of $250 \ V$ and $100 \ W$ are first connected in series and then in parallel with a supply of $250 \ V$. Total power in each of the cases will be . . . . . . respectively.

An electric kettle takes $4 \ A$ current at $220 \ V$. If the entire electric energy is converted into heat energy, then the time (in minutes) taken to increase the temperature of $1 \ kg$ of water from $34^{\circ} C$ to $100^{\circ} C$ is

The battery of a mobile phone is rated as $4.2 \ V, 5800 \ mAh$. How much energy is stored in it when fully charged (in $kJ$)?

$A$ constant voltage is applied between the two ends of a metallic wire. If both the length and the radius of the wire are doubled, the rate of heat developed in the wire

One kilowatt hour is equal to