[Physics] Application of Displacement Current


I'm reasonably happy with the derivation and results of displacement current, however, I'd like to be aware of a few practical applications of this idea.

So far, the only one I'm aware of is when finding the magnetic field in between a capacitor using Ampere's Law. In such a case $I_c=0$ and $I_D$ has some definite non-zero value so as to account for the magnetic field we can physically measure in between the plates of the capacitor.

What are other examples can you throw at me ?

Best Answer

Electromagnetic radiation requires the displacement current term in Maxwell's equations:

  • Faraday's law implies that a time-varying magnetic field induces an electric field.

  • The equation for the curl of the magnetic field shows that a time-varying electric field (the displacement current) produces a magnetic field.

The interplay of these two effects (in a charge and current-free region) results in the wave equation, whose solutions are propagating electromagnetic fields (radiation).