= Alternating-current drift excursion
For sinusoidal <current density> $J(t)=J_{\rm pk}\cos(\omega t)$ and constant <carrier density> $n$, the <Electron> <drift velocity> is $v_d(t)=-J_{\rm pk}\cos(\omega t)/(ne)$. Its displacement has amplitude $J_{\rm pk}/(ne\omega)$ and zero net change over a full cycle. The distance accumulated by this drift alone in one cycle is $4v_{\rm pk}/\omega=2v_{\rm pk}/(\pi f)$. With an RMS current, $v_{\rm pk}=\sqrt2v_{\rm rms}$. This does not measure the much larger microscopic path due to <Fermi velocity> and <electron-phonon scattering>.
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