How many calories of heat will be produced approximately in a $210\, W$ electric bulb in $5$ minutes?

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

$A\, 5\, ^oC$ rise in the temperature is observed in a conductor by passing some current. When the current is doubled,then the rise in temperature will be equal to ............. $^oC$.

$A$ house is served by a $220 \, V$ supply line in a circuit protected by a $9 \, A$ fuse. What is the maximum number of $60 \, W$ lamps in parallel that can be turned on simultaneously?

An electric bulb of $100\, W$ is connected to a supply of electricity of $220\, V$. The resistance of the filament is ............. $\Omega$.

$A$ 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 .............. $\Omega$.