Current and magnetic fields

  • #1
Rav430
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Why does current produce a static magnetic field, but a static magnetic field doesn't produce current?

Specifically, why is one true, but the inverse not true? I can accept that each rule individually is just how the universe works... but it sounds so contradictory when I examine both together.

Is there some way I can think about this intuitively?
 

Answers and Replies

  • #2
lekh2003
Gold Member
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Because a current is a changing electrical charge. Charge is moving. This is why it generates a magnetic field.

A magnetic field needs to be moving in a similar way for it to produce an electric field.
 
  • #3
Dale
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2021 Award
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Why does current produce a static magnetic field, but a static magnetic field doesn't produce current?
Jefimenko’s equations and the retarded potentials are pretty clear about the temporal and spatial ordering. A current here now causes a magnetic field elsewhere at the retarded time. You simply cannot swap the two roles. The cause preceeds the effect and the equation cannot be reversed to get the effect preceding the cause
 
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