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

An electric bulb rated $50 \, W-200 \, V$ is connected across a $100 \, V$ supply. The power dissipation of the bulb is: (in $ \, W$)

$A$ constant current $i$ is passed through a resistor. Taking the temperature coefficient of resistance into account,indicate which of the plots shown in the figure best represents the rate of production of thermal energy in the resistor.

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.

How much heat (in $cal$) is produced when a $210 \, W$ bulb is kept on for $5 \, min$? (Given $J = 4.2 \, J/cal$)

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