Electric Charge and Magnetism: Constant or Varying Magnetic Field?

In summary, an electric charge moving with constant velocity creates a constant magnetic field. If the charge is accelerated, it will generate radiation (time varying magnetic field).
  • #1
Dikshant
12
0
If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
 
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  • #2
Dikshant said:
If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
Does a wire with a constant current through it create a magnetic field?
 
  • #3
Vagn said:
Does a wire with a constant current through it create a magnetic field?
Thanks for reply,but m already a bit confused and that's a different case.
 
  • #4
Vagn said:
Does a wire with a constant current through it create a magnetic field?
Yeah,a constant magnetic field
 
  • #6
ChrisVer said:
yes it generates a constant in time magnetic field following the Biot Servart law
http://maxwell.ucdavis.edu/~electro/magnetic_field/pointcharge.html

If it is accelerated it is going to generate radiation (time varying magnetic field)
And
ChrisVer said:
yes it generates a constant in time magnetic field following the Biot Servart law
http://maxwell.ucdavis.edu/~electro/magnetic_field/pointcharge.html

If it is accelerated it is going to generate radiation (time varying magnetic field)

And what happens when a varying electric field is working in an area??
ChrisVer said:
yes it generates a constant in time magnetic field following the Biot Servart law
http://maxwell.ucdavis.edu/~electro/magnetic_field/pointcharge.html

If it is accelerated it is going to generate radiation (time varying magnetic field)[/QAnd
 
  • #7
Dikshant said:
If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?
The fields from a moving charge are given by the Lienard Wiechert potentials

http://en.wikipedia.org/wiki/Liénar...onding_values_of_electric_and_magnetic_fields

It doesn't have an explicit time dependence, but the input variables are functions of time so the result is also.
 
  • #9
Yes you are right DaleSpam...
Indeed, I misinterpreted this...I also thought about that when I saw the [itex]r[/itex] in the equation, but then... I got confused with the [itex]u=const[/itex] case not generating electromagnetic radiation... but the EM radiation is something different (has to do with the Poynting vector as well)...
 
  • #10
Yes that is correct. The fields generated by the Biot Savart law or the Lienard Wiechert potential for constant velocity do not generate "radiation". The fields stay localized to the charge. They change over time, as the charge moves, but their relationship to the charge doesn't change.
 
  • #11
Thank you all
 

1. What is the relationship between moving charges and magnetism?

The relationship between moving charges and magnetism is known as electromagnetism. When an electric current flows through a wire, it creates a magnetic field around the wire. Similarly, when a magnetic field is applied to a wire, it can induce an electric current in the wire. This phenomenon is known as electromagnetic induction.

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

A permanent magnet is a material that produces a magnetic field without the need for an external source of electricity. It is made of ferromagnetic materials such as iron, cobalt, or nickel. On the other hand, an electromagnet is a coil of wire that produces a magnetic field when an electric current is passed through it. The strength of the magnetic field in an electromagnet can be controlled by changing the amount of current flowing through the wire.

3. How does the direction of a magnetic field depend on the direction of the current?

The direction of a magnetic field around a current-carrying wire follows the right-hand rule. If you wrap your right hand around the wire with your thumb pointing in the direction of the current, your fingers will curl in the direction of the magnetic field.

4. What is the role of moving charges in creating a magnetic field?

Moving charges are essential in creating a magnetic field. When charges move, they create a magnetic field around them. This is because moving charges are surrounded by an electric field, and when they move, the electric field becomes distorted, resulting in a magnetic field. The strength of the magnetic field is proportional to the speed of the moving charges.

5. How is the strength of a magnetic field affected by the distance from the source?

The strength of a magnetic field decreases as the distance from the source increases. This is known as the inverse-square law. The strength of a magnetic field is inversely proportional to the square of the distance from the source. This means that the farther you are from the source, the weaker the magnetic field will be.

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