Why Does Current Produce a Magnetic Field But Not Vice Versa?

In summary, a current produces a static magnetic field because a current is a changing electrical charge that is moving, which generates a magnetic field. On the other hand, a static magnetic field does not produce current because the cause (the current) must precede the effect (the magnetic field) and cannot be reversed. Jefimenko’s equations and the retarded potentials support this temporal and spatial ordering.
  • #1
Rav430
1
0
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?
 
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  • #2
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
Rav430 said:
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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Related to Why Does Current Produce a Magnetic Field But Not Vice Versa?

What is the relationship between current and magnetic fields?

The relationship between current and magnetic fields is described by Ampere's Law, which states that a magnetic field is produced around a current-carrying wire. The strength of the magnetic field is directly proportional to the current and inversely proportional to the distance from the wire.

How is the direction of a magnetic field determined?

The direction of a magnetic field is determined by the right-hand rule. If the current is flowing in the direction of your fingers, then your thumb will point in the direction of the magnetic field lines.

What is the difference between a permanent magnet and an electromagnet?

A permanent magnet is a material that produces a magnetic field on its own, while an electromagnet is created by running an electric current through a wire wrapped around a magnetic material. The strength of an electromagnet can be controlled by adjusting the current, while a permanent magnet's strength is fixed.

What is the significance of magnetic fields in everyday life?

Magnetic fields play a crucial role in everyday life, from powering motors and generators to guiding compass needles. They are also used in medical technology such as MRI machines and in the production of electricity from renewable sources like wind turbines.

How do magnetic fields interact with each other?

Magnetic fields interact with each other in a similar way to electric fields. Like poles (North and North or South and South) repel each other, while opposite poles (North and South) attract. The strength of the interaction depends on the distance between the magnets and their relative strengths.

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