The total power dissipated in watts in the circuit shown is ............. $W$

The internal resistance of a primary cell is $4\, ohm$. It generates a current of $0.2\, amp$ in an external resistance of $21\, ohm$. The rate at which chemical energy is consumed in providing the current is .............. $J/s$

$A$ wire of length $L$ and $3$ identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by $\Delta T$ in time $t. N$ number of similar cells is now connected in series with a wire of the same material and cross section but of length $2L$. The temperature of the wire is raised by the same amount $\Delta T$ in the same time $t$. The value of $N$ is :

A heating coil can heat the water of a vessel from $20\,^oC$ to $60\,^oC$ in $30$ minutes. Two such heating coils are put in series and then used to heat the same amount of water through the same temperature range. The time taken now will be ............ $min$ (neglecting thermal capacity of the coils)

An electric bulb of $500 \,watt$ at $100\, volt$ is used in a circuit having a $200\, {V}$ supply. Calculate the resistance ${R}$ to be connected in series with the bulb so that the power delivered by the bulb is $500\, {W}$. (in $\Omega$)

The heat produced by a $100\, watt$ heater in $2$ minute will be equal to