1. What does an electric circuit mean?

2. Define the unit of current.

3. Calculate the number of electrons constituting one coulomb of charge.

1. An electric circuit is a continuous and closed path for passing the current.

2. Ampere(A) is the unit of current.

3. As known, charge on one electron $=1.6\times10^{-19}\ C$

Or $1\ C=\frac{1}{1.6\times10^{-19}}$

Or $1\ C=6.25\times10^{18}$