I’ve got to do a small summary of what this formula is used for and what each of the letters stand for.
I= Current in a conductor
n= number of charge carriers per unit volume(usually they are electrons but can also be other species that carry any type of charge)
q= charge on an electron
v= drift velocity of the charge carriers
A= Area of the conductor on which the charges ate moving.
This formula is used to calculate the current carried by a conductor in which we know the charge carrier density and the drift velocity of the charge carriers.