Current \((I)\)
the rate of flow of electric charge past a point or region
Elementary Charge
Coulomb
Ampere
Ohm
Siemens
$$1\ Coulomb = 1.036 * 10^{-5}\ mols \cdot Na \cdot elementary\ charges$$
$$1\ Elementary\ Charge = 1.602176634 * 10^{-19}\ Coulombs$$
$$1\ Ampere\ (A)(Amp) = \frac{1\ Coulomb}{1\ Second}$$
$$1\ Coulomb\ (A)(Amp) = 1\ Ampere * 1\ Second$$
$$1\ Ohm\ (\Omega) = \frac{1\ Joule \cdot Second}{1\ Coulomb^2}$$
$$1\ Siemen\ (S) = [\Omega^{-1}] = \frac{1\ Ampere\ (A)}{1\ Volt}$$
$$1\ Siemen\ (S) = \frac{1\ Coulomb^2}{1\ Joule \cdot Second}$$
$$1\ Volt = \frac{1\ Joule}{1\ Coulomb}$$
$$Conductance\ (G) = \frac{1}{Resistance} = \frac{Current\ (I)}{Voltage\ (V)} = Siemens$$
$$Current\ (I)\ or\ (A) = \frac{1\ Coulomb}{1\ Second}$$
$$Current\ (I)\ or\ (A) = \frac{1\ Volt\ (V)}{1\ Ohm\ (\Omega)}$$
Calculate Current from Voltage and Resistance
$$Current\ (I) = \frac{Voltage\ (V)}{Resistance\ (Ohms)(\Omega)}$$
Calculate Current from Membrane Potential, Ion's Conductance, and Ion's Equalibrium Potential
$$Current\ of\ Ion \ (I) = \text{Ion's}\ Conductance\ (G) * \left(\ Membrane\ Potential\ (V_m) - \text{Ion's}\ Equalibirum\ Potentail\ (E)\ \right)$$
$$Current\ of\ Ion\ (I) = \text{Ion's}\ Conductance\ (G) * \left(\ \text{Ion's}\ Driving\ Force\ \right)$$