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

If two wires having resistance $R$ and $2R$. Both joined in series and in parallel then ratio of heat generated in this situation, applying the same voltage,

The ratio of powers dissipatted respectively in $R$ and $3R$, as shown is:

Which device can convert all electrical energy into heat

A coil takes $15\,\min$ to boil a certain amount of water, another coil takes $20\,\min$ for the same process. Time taken to boil the same amount of water when both coil are connected in series ........... $min$

A wire when connected to $220\,V$ mains supply has power dissipation ${P_1}$. Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is ${P_2}$. Then ${P_2}:{P_1}$ is