Does a time varying magnetic field in vacuum produce electric field or not?

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Discussion Overview

The discussion centers on whether a time-varying magnetic field in a vacuum produces an electric field, particularly in the context of a charged particle near a current-carrying wire with varying current. Participants explore the implications of electromagnetic theory, specifically referencing the relationship between changing magnetic fields and electric fields.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that a time-varying magnetic field should produce an electric field, which would then exert a force on a charged particle at rest.
  • Others argue that since the charged particle is initially at rest, it would not experience a force from the magnetic field directly, as per the equation F = q*(VxB).
  • There is a question about whether an electric field is produced at a specific point in space where only a changing magnetic field exists.
  • Some participants clarify that changing magnetic fields are sources of circulating electric fields, referencing the Maxwell-Faraday equation.
  • It is noted that one cannot have a changing magnetic field without also having an associated electric field, challenging the notion of a magnetic field existing in isolation.
  • Participants discuss the idea of viewing electric and magnetic fields as components of a unified electromagnetic field rather than as separate entities.

Areas of Agreement / Disagreement

Participants express differing views on the implications of a time-varying magnetic field, with some asserting that it must produce an electric field while others question the conditions under which this occurs. The discussion remains unresolved regarding the specifics of how and where electric fields arise from changing magnetic fields.

Contextual Notes

Participants express uncertainty about the conditions necessary for electric fields to arise from magnetic fields, and there are references to fundamental equations of electromagnetism without reaching a consensus on the interpretation of these concepts.

yashraj
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TL;DR
Will a charged particle at rest experience a force on it due to the electric field produced by a time varying magnetic field in vacuum.
Suppose there is very long current carrying wire. A charged particle is present somewhere around it. The current in the wire varies with time, thus by biot-savart's law there should be time varying magnetic field. I want to know that will this time varying magnetic field produce electric field or not ? If it produces electric field then the charged particle initially present at rest will experience a electric force on it.
 
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yashraj said:
TL;DR Summary: Will a charged particle at rest experience a force on it due to the electric field produced by a time varying magnetic field in vacuum.

Suppose there is very long current carrying wire. A charged particle is present somewhere around it. The current in the wire varies with time, thus by biot-savart's law there should be time varying magnetic field. I want to know that will this time varying magnetic field produce electric field or not ? If it produces electric field then the charged particle initially present at rest will experience an electric force on it.
Yes.
 
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kuruman said:
Yes.
How ? I mean initially charge was at rest. So whatever be the magnetic field either changing or constant, the force on charge due to this magnetic field according to this relation F = q*(VxB) should be zero, so this charge at rest shouldn't experience force due to magnetic field at this instant. What doubt right now i am having is that how could changing magnetic field can produce electric field in vacuum ?
 
yashraj said:
How ?
Because, as you noted, a time-varying magnetic field implies the presence of an electric field. So the particle moves under the influence of the electric field.
yashraj said:
What doubt right now i am having is that how could changing magnetic field can produce electric field in vacuum ?
I guess the question is why you think it shouldn't.
 
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Ibix said:
Because, as you noted, a time-varying magnetic field implies the presence of an electric field. So the particle moves under the influence of the electric field.
I guess the question is why you think it shouldn't.
Thank you for the clarification. But I don't understand that if at a point "A" there is only one field that is magnetic field "B" and this magnetic field is changing with time then would there be electric field produced at point "A" or not ?
 
yashraj said:
Thank you for the clarification. But I don't understand that if at a point "A" there is only one field that is magnetic field "B" and this magnetic field is changing with time then would there be electric field produced at point "A" or not ?
Not quite. Roughly speaking, magnetic field lines varying in time are sources of circulating electric field lines about them. If free charges happen to be around, they will be accelerated by them. This is the Maxwell-Faraday equation, one of the 4 Maxwell's equations. read about it here.
 
yashraj said:
Thank you for the clarification. But I don't understand that if at a point "A" there is only one field that is magnetic field "B" and this magnetic field is changing with time then would there be electric field produced at point "A" or not ?
You can't have "only a magnetic field that is changing" - there will always be an electric field if there is a changing magnetic field. You can have an unchanging magnetic field and no electric field, and then you can start the magnetic field changing and an electric field will appear, if that's what you mean.

I think that it's probably better to think of the electromagnetic field, some components of which we call the electric field and some we call the magnetic field, rather than thinking of the electric and magnetic fields as separate things.
 
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Ibix said:
You can't have "only a magnetic field that is changing" - there will always be an electric field if there is a changing magnetic field. You can have an unchanging magnetic field and no electric field, and then you can start the magnetic field changing and an electric field will appear, if that's what you mean.

I think that it's probably better to think of the electromagnetic field, some components of which we call the electric field and some we call the magnetic field, rather than thinking of the electric and magnetic fields as separate things.
Your answer now gave me some better clarity. Thank you for helping me.
 
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