Find the number of electrons flowing through the filament of a $120 \ V, 60 \ W$ electric lamp in one second.

If two electric bulbs have $40\,W$ and $60\,W$ ratings at $220\,V$,then the ratio of their resistances will be

$A$ uniform heating wire of resistance $36 \, \Omega$ is connected across a potential difference of $240 \, V$. The wire is then cut into half and a potential difference of $240 \, V$ is applied across each half separately. The ratio of power dissipation in the first case to the total power dissipation in the second case would be $1:x$,where $x$ is........... .

If $10$ bulbs of $50\,W$ are used for $10$ hours a day,how many units of electricity will be consumed in a month ($30$ days)?

The same mass of copper is drawn into two wires $1 \, mm$ and $2 \, mm$ thick. Two wires are connected in series and current is passed through them. The ratio of heat produced in the wires is:

If the power in the external resistance $R$ is maximum,then which of the following statements are correct?
$(i) R = r$
$(ii)$ Power in $R$ is $\frac{E^2}{4R}$
$(iii)$ Input power is $\frac{E^2}{2R}$
$(iv)$ Efficiency is $50\%$