$A$ $5\;A$ fuse wire can withstand a maximum power of $1\;W$ in the circuit. The resistance of the fuse wire is

$A$ lamp is rated at $240 \ V, 60 \ W$. When in use,the resistance of the filament of the lamp is $20$ times that of the cold filament. The resistance of the lamp when not in use is: (in $Omega$)

An electric heater is marked with $220\, V$ and $1100\, W$. If it is used for $4\, hours$, the energy consumed in $kWh$ will be:

From where does electrical power derive? Explain it.

An electric lamp is marked $60\, W$, $230\, V$. The cost of $1\, kWh$ of power is Rs. $1.25$. The cost of using this lamp for $8$ hours is Rs. ................

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 $50\%$