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Displacement current
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Allows current continuity through capacitors.
Between capacitor plates there's no charge flow but a changing electric field acts as a current: I_d = ε₀ dΦ_E/dt, completing the current loop and producing a magnetic field.
Equal to the conduction current in wires.
Introduced by Maxwell.
In more detail
Displacement current is the term ε0 dE/dt added by Maxwell to Ampère's law. It explains how a changing electric field generates a magnetic field, even in the absence of conduction current.
Real-world uses
- Displacement current explains the magnetic field between charging capacitor plates.
- It is essential for the theory of electromagnetic waves.
- Engineers use the concept of displacement current to explain how current seems to pass through a capacitor.
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Frequently asked questions
Between capacitor plates, is there current?
No conduction current, but the displacement current produces the magnetic field there.
Why is it not a real current?
It is a changing electric field, not a flow of charge.
Does current really cross a capacitor gap?
No. The changing electric field between the plates acts as a displacement current, which keeps the total current continuous.
Related topics in AC Circuits & EM Waves
Transformers in power transmission · Three-phase power · Rectification and smoothing · EM wave generation · EM wave properties · Speed of light