An electrical power line, having a total resistance of $2 \, \Omega$, delivers $1 \, kW$ at $220 \, V$. The efficiency of the transmission line is approximately $....... \%$.

$A$ circular wire has a current density $J = (2 \times 10^{10} \text{ A/m}^2) r^2$, where $r$ is the radial distance from the center and the wire radius is $2 \text{ mm}$. The potential difference applied across the wire is $50 \text{ V}$. How much energy (in Joules) is converted to thermal energy in $100 \text{ s}$ (in $\pi$)?

$A$ bulb has a specification of $1\, kW$ and $250\, V$. The resistance of the bulb is .................. $\Omega$.

How many $60 \,W$ bulbs may be safely run on $220 \,V$ using a $5 \,A$ fuse?

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

$A$ piece of fuse wire melts when a current of $15\, A$ flows through it. With this current,if it dissipates $22.5\, W$,the resistance of the fuse wire will be .............. $\Omega$.