Does a straight non-time-dependent E field create a circular B field?

In summary, the conversation is discussing the relationship between Electric and Magnetic fields and whether a non-time dependent E field can create a circular B field. The discussion also touches on relativity and how it affects the understanding of the electromagnetic field. Ultimately, it is concluded that in the given example, the current in a wire is what creates the B field, not the E field.
  • #1
zheng89120
149
0
I was under the impression that it does, you know from Ampere's law. But today, my professor told me that Electric and Magnetic fields are very similar (although I can't imagine they are exactly the same, since there are no magnetic monopoles), THAT a non-time dependent E field does not create a circular B field. Does this mean that a current in a wire is actually a time-dependent E field?

Thanks.

PS. the course that this was from was Relativistic Electrodynamics.
 
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  • #2
No, in this example there is no E field. It's the current in the wire that creates the B field.
 
  • #3
Nevertheless, relativity tells us that there is not a separated E and B field, but only one electromagnetic field. If you have in one frame of reference a pure electrostatic E field in another frame of reference, moving relative to the first, you have both an E and a B field. Both fields together make up the electromagnetic field. (E,B) are the components of an antisymmetric 2nd-rank tensor in Minkowski space.
 
  • #4
That's quite true, but has nothing to do with the present thread. The question was, "is the current in a wire actually a time-dependent E field?" and the answer is no.
 
  • #5
Bill_K said:
No, in this example there is no E field. It's the current in the wire that creates the B field.

Actually, there was at some moment an E field (for the current to be there in the first place) but no longer there is, whether one decides to attribute the B field to this E field change or to the actual current it makes no difference at all.
 

1. What is a straight non-time-dependent E field?

A straight non-time-dependent E field is an electric field that is constant in magnitude and direction and does not change over time. This type of field is typically produced by a stationary electric charge or a constant voltage source.

2. How is a circular B field created?

A circular B field is created when there is a changing electric field, either in magnitude or direction. This changing electric field can be produced by a time-varying current or by a moving charge.

3. Does a straight non-time-dependent E field always create a circular B field?

No, a straight non-time-dependent E field does not always create a circular B field. As mentioned earlier, a changing electric field is required to produce a circular B field. If the electric field is constant and does not change over time, it will not create a circular B field.

4. What is the relationship between E field and B field?

The E field and B field are two components of the electromagnetic field. They are both perpendicular to each other and are essential in understanding the behavior of electrically charged particles. The E field is responsible for the attraction and repulsion of electric charges, while the B field is responsible for the magnetic force experienced by moving charges.

5. Can a circular B field exist without an E field?

No, a circular B field cannot exist without an E field. According to Maxwell's equations, a changing electric field is necessary to produce a magnetic field. Therefore, a constant B field without an accompanying E field is not possible.

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