The energy consumed in a $1\, kW$ electric heater in $30$ seconds will be:

An electric bulb is marked $100\ W, 230\ V$. If the supply voltage drops to $115\ V$,how much heat (in $J$) is produced by the bulb in $20\ min$?

$n$ identical bulbs,each designed to draw a power $P$ from a certain voltage supply,are joined in series across that supply. The total power which they will draw is

$A$ ($100\, W$,$200\, V$) bulb is connected to a $160\, V$ power supply. The power consumption would be ............. $W$.

The resistance of an electrical toaster has a temperature dependence given by $R(T) = R_0[1 + \alpha(T - T_0)]$ in its range of operation. At $T_0 = 300\,K, R = 100\,\Omega$ and at $T = 500\,K, R = 120\,\Omega$. The toaster is connected to a voltage source of $200\,V$ and its temperature is raised at a constant rate from $300\,K$ to $500\,K$ in $30\,s$. The total work done in raising the temperature is:

An amount of charge $Q$ passes through a coil of resistance $R$. If the current in the coil decreases to zero at a uniform rate during time $T$, then the amount of heat generated in the coil will be,