Quasistatic approximation (electromagnetism, $\omega L/c\ll 1$)

An approximation that keeps slow electromagnetic time variation while treating propagation across characteristic size $L$ as rapid compared with the variation time $1/\omega$. The dimensionless parameter $\omega L/c$ measures that separation. Which terms of the Maxwell equations can be dropped still depends on the physical scaling; small propagation delay alone does not justify deleting both displacement current and electromagnetic induction. For a slowly driven parallel-plate capacitor, a nearly uniform gap electric field can coexist with the magnetic field generated by its changing electric flux.