An electric current $I$ appears in the list of formulae on page 3 as $I = Anvq$. What does each symbol stand for in the expression for an electric current in a metal wire?
- A$A$: area of cross-section; $n$: number of free electrons; $v$: voltage; $q$: charge of each molecule
- B$A$: area of cross-section; $n$: number of free electrons per unit volume; $v$: average drift speed of electrons; $q$: charge of each electron
- C$A$: current; $n$: number of free electrons; $v$: average drift speed of electrons; $q$: charge of each molecule
- D$A$: current; $n$: number of free electrons per unit volume; $v$: voltage; $q$: charge of each electron