What is the $SI$ unit of electric charge?

Three incandescent bulbs of $100\, W$ each are connected in series in an electric circuit. In another circuit, another set of three bulbs of the same wattage are connected in parallel to the same source. Will the bulbs in the two circuits glow with the same brightness? Justify your answer.

Out of the two,a toaster of $1\, kW$ and an electric heater of $2\, kW$,which has a greater resistance?

How many electrons will there be in $1.6 \ C$ charge?

Derive the relation $R = R_{1} + R_{2} + R_{3}$ when three resistors $R_{1}, R_{2}$ and $R_{3}$ are connected in series in an electric circuit.

The potential difference between the terminals of an electric heater is $60\, V$ when it draws a current of $4\, A$ from the source. What current will the heater draw,if the potential difference is increased to $120\, V$ (in $, A$)?