PrepZii

formula

Current, Drift Velocity and Current Density

The source defines average and instantaneous current, conductor current, drift velocity, and current density.

I_{av}=\frac{\Delta q}{\Delta t}

i=\lim_{\Delta t\to0}\frac{\Delta q}{\Delta t}=\frac{dq}{dt}

I=nAeV_d

v_d=\frac{\lambda}{\tau}

v_d=\frac{1}{2}\frac{eE}{m}\tau

\vec J=\frac{dI}{ds}\hat n

$q$

charge

$E$

electric field or energy depending on context