Which device uses direct current $(DC)$?

Calculate the number of electrons constituting one coulomb of charge.

The formula for an electric current is $.....$

If a current of $0.5\;A$ is passed through an electric bulb for $1\;hour$, how much electric charge will pass through the bulb (in $C$)?

An electric appliance draws a current of $0.4\, A$ when the voltage is $200\, V$. Calculate the amount of charge flowing through it in one hour.

What is the unit of electric current?