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Maxwell's displacement current
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Changing electric fields also produce magnetic fields.
I_d = ε₀dΦ_E/dtA changing electric field acts like a current: I_d = ε₀ dΦ_E/dt. With it, Ampère's law becomes ∮B·dl = μ₀(I + I_d), predicting EM waves.
It makes the current continuous through a charging capacitor.
Needed for charge conservation.
In more detail
Maxwell added a displacement current term, ε0 dΦE/dt, to Ampère's law. This term shows that a changing electric field produces a magnetic field, which is essential for electromagnetic waves.
Real-world uses
- Maxwell's equations predict radio waves and light.
- Capacitors in circuits have displacement current between plates.
- Maxwell realised that a changing electric field produces a magnetic field, which explains how capacitors carry current.
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Frequently asked questions
Is displacement current a real current?
It is not a flow of charge, but it produces magnetic fields like real current does.
Why was it important?
It made Ampère's law consistent with charge conservation and predicted electromagnetic waves.
Is displacement current a real current?
It is not a flow of charge, but it produces a magnetic field just as a real current does.
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