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

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

$A$ resistor develops $500 \, J$ of thermal energy in $20 \, s$ when a current of $1.5 \, A$ is passed through it. If the current is increased from $1.5 \, A$ to $3 \, A$,what will be the energy (in $J$) developed in $20 \, s$?

Heating coils rated at $220\, V$ are available with resistances of $55\,\Omega$,$110\,\Omega$,$220\,\Omega$,and $440\,\Omega$. Which resistance value will produce the maximum power?

Two bulbs are rated $(40 \; W, 200 \; V)$ and $(100 \; W, 200 \; V)$. What is the correct relation for their resistances?

$A$ resistance $R = 12 \, \Omega$ is connected across a source of $emf$ as shown in the figure. Its $emf$ changes with time as shown in the graph. What is the heat developed in the resistance in the first four seconds (in $, J$)?