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

$A$ 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.

$A$ current $i$ passes through a wire of length $l$, radius of cross-section $r$ and resistivity $\rho$. The rate of heat generation is

Which device can convert all electrical energy into heat?

The resistance of a bulb filament changes with temperature. If a bulb rated at $220 \ V$ and $100 \ W$ is connected to a supply of $(220 \times 0.8) \ V$,the actual power consumed will be:

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