Electric current: 1 Amp (A) = 1 Coulomb (C) per second (s)
= (density, charge, speed, Area)
where =current density.
= electric field where = resistivity
, and ,
where is resistance
where =internal resistance and =emf.
Kirchhoff Junction: and Loop:
Charging an RC (resistor-capacitor) circuit: and
where is RC time, and .
Discharging an RC circuit: and