Electric current : the amount of charge per unit time that crosses the imaginary surface of a wire.
I = Δ Q /Δt
- I electric current in A
- ΔQ the charge passed in C (1 Coulomb is the unit of charge)
- Δt time in s (!)
Example
The electric current in a wire is 500 mA.
Calculate the charge passed through the imaginary surface of the wire in 2.0 min
I = Δ Q /Δt
0.5 = Δ Q/120
Δ Q = (0.5)( 120) = 60 C