The origin of self inductance in a current loop?

In summary: So, radiation is an effect of inductance.In summary, radiation is caused by inductance and it is an effect of the cosmic speed limit.
  • #1
ZeroGravity
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Hi Forum

I am trying to get a better grasp of the relation between electric field and the magnetic field.
The overall question is "What is The origin of selfinductance in a current loop?"
Here are my thourghts:

A battery is connected to a say circular wire with some resistance. The current builds up in the magnetic field and the rest as heat in the wire. The energy U in the magnetic field is U=0.5*L*I^2 L being the selfinductance and I the current. The energy in the magnetic field is "returned" then the battery is removed freom the circuit.

But what is the origin og the Induced EMF(ElectroMotoricForce)?

I know from Feynman's lectures Vol II 13.6. that foro two straight wires the magnetic field from wire one, acts on wire two with a force. But viewed from a refrence frame moving with the electrons, the magnetic field is transformed into an electric field, and the force is now seen as a coulomb force.

Is that the same case for a current loop?

What happens if the reference frame rotates?

Thanks all !
Martin
 
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  • #2
The induced EMF is due to the changing magnetic field. When the battery is removed from the circuit, the current begins to decay, and so the magnetic field begins to decrease. The changing magnetic field induces an electric field through Maxwells' equation [itex] \nabla \times E =- \frac{\partial B}{\partial t}[/itex]
 
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  • #3
phyzguy said:
The induced EMF is due to the changing magnetic field. When the battery is removed from the circuit, the current begins to decay, and so the magnetic field begins to decrease. The changing magnetic field induces an electric field through Maxwells' equation [itex] \nabla \times E =- \frac{\partial B}{\partial t}[/itex]
To Zero Gravity: And to take a mechanical analogy, the inductor displays "inertia". It is hard to get the current moving and hard to stop it. The inductor stores energy in its magnetic field and in order to stop the current we need to apply a braking force. This is a reverse voltage, which can be obtained by inserting a high resistance, or opening the switch etc.
 
  • #4
ZeroGravity said:
I am trying to get a better grasp of the relation between electric field and the magnetic field.
The overall question is "What is The origin of selfinductance in a current loop?"

First take a look at the part titled "Radiation as a Consequence of the Cosmic speed limit" here:
http://physics.weber.edu/schroeder/mrr/MRRtalk.html

And then see the part titled "Compared to the far field" here:
https://en.wikipedia.org/wiki/Near_and_far_field

First link explains origin of radiation, second link explains that induction is related to radiation.
 
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1. What is self inductance?

Self inductance is a property of a conductive material that describes its ability to resist changes in electric current flowing through it. It is caused by the magnetic field that is created by the current itself.

2. How is self inductance measured?

Self inductance is measured in units called henrys (H). The value of self inductance depends on factors such as the geometry and material of the conductive material, as well as the number of turns in a coil.

3. What is the origin of self inductance in a current loop?

The origin of self inductance in a current loop is the magnetic field that is created by the current flowing through the loop. This magnetic field induces a voltage in the loop, which opposes any changes in the current.

4. How does self inductance affect the behavior of a circuit?

Self inductance can cause a delay in the response of a circuit to changes in the current, as the induced voltage opposes the change. This can result in a phenomenon known as inductive kick, where a sudden change in current can generate a high voltage spike.

5. Can self inductance be beneficial in a circuit?

Yes, self inductance can be beneficial in certain circuits. It can be used to store energy in the form of a magnetic field, which can then be released when the current changes. This is the principle behind devices such as inductors and transformers, which are commonly used in electronics.

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