Displacement current

Definition

Displacement current is a term in Maxwell's equations that accounts for the changing electric field in regions where there is no physical movement of charge. It allows Ampère's law to be consistent with the continuity equation and is essential for explaining electromagnetic waves.

5 Must Know Facts For Your Next Test

1. It was introduced by James Clerk Maxwell to extend Ampère's law.
2. The displacement current density is given by $\varepsilon_0 \frac{\partial E}{\partial t}$, where $E$ is the electric field and $\varepsilon_0$ is the permittivity of free space.
3. It enables the formation of electromagnetic waves by ensuring that changing electric fields can create magnetic fields even in a vacuum.
4. The concept of displacement current leads to the unification of electricity and magnetism into electromagnetism.
5. It plays a crucial role in predicting that light is an electromagnetic wave.

Review Questions

• What equation includes the displacement current term?
• How does displacement current contribute to the generation of electromagnetic waves?
• What physical constant appears in the expression for displacement current density?

Related terms

Maxwell's Equations:

A set of four fundamental equations that describe how electric and magnetic fields interact and propagate.

Ampère's Law:

One of Maxwell's equations, it relates magnetic fields to the electric currents that produce them, including a term for displacement current.

Electromagnetic Waves:

Waves composed of oscillating electric and magnetic fields, which travel through space at the speed of light.