Two electric bulbs whose resistances are in the ratio of $1:2$ are connected in series. The powers dissipated in them have the ratio:

By what percentage will the illumination of the lamp decrease if the current drops by $20 \%$ (in $\%$)?

An electric room radiator which operates at $225\, V$ has a resistance of $50\, \Omega$. The power of the radiator is approximately ............... $W$.

$A$ heater draws a current of $2\,A$ when connected to a $250\,V$ source. The rate of energy dissipation is ............. $W$.

What is the value of $1 \, kWh$ in Joules?

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