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

Two equal resistances when connected in series to a battery, consume electric power of $60\,W.$ If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be .............. $W$

An electric bulb marked $40\, W$ and $200\, V$, is used in a circuit of supply voltage $100\, V$. Now its power is

A current source drives a current in a coil of resistance $R_1$ for a time $t$. The same source drives current in another coil of resistance $R_2$ for same time. If heat generated is same, find internal resistance of source.

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 ........... $min$

Two wires $A$ and $B$ of same material and mass have their lengths in the ratio $1 : 2$. On connecting them to the same source, the rate of heat dissipation in $B$ is found to be $5\,W$. The rate of heat dissipation in $A$ is............ $W$