Electrons and drift in code

You will write three small functions about the current in a copper wire. They use $I = nAev_d$.

The idea. One electron has a charge of $1.6 \times 10^{-19}$ C. Copper has $8.5 \times 10^{28}$ free electrons in each cubic metre. Areas are in m².

Your tasks.

1. In electrons_per_second, return the number of electrons that cross a section each second, for a current I in A.
2. In drift_speed, return the drift speed in m/s, for a current I in A in a wire of cross section A in m².
3. In current_density, return the current density in A/m².