Displacement Current:-

Displacement Current:-

Lets define current first. Current is when charge passes through a plane. Plane can be anything from being in space or for that matter opposite plate of the capacitor!

1. If we think of displacement current in physical/pure physics way - When you start charging one plate of cap, the other starts to get opposite charge. Energy is being passed from one point to other (simply speaking...rate of transfer of evergy, leads to power, leads to = I^2*R, where R is 337 Ohm aprox. and I is displacement current by the way... will come to this later). It will only happen in transient state, the energy travels on the back of the entity called displacement current. It is not something that just exists in equations to satisfy some void.

2. Since there is no energy flow, no power delivered, no change of potential from one value to other, there is literally no one doing anything in static field. Hence displacement current is non-existing in this case. If you read through any antenna or EM energy book, you'd come across the same guy that carries energy ahead.

I would want to mention though, when you place a static charge in space, from the instance it was placed to the instance it exists, that period is of "Step transient". Something green's function in mathematics defines such phenomenon. So there is no such perfect static field thing in nature. So where ever you turn, you'll see displacement currents all around you... even in static fields... when they are propagating that is :)