Electric charges moving and magnetic field

  • Thread starter haiha
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  • #1
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I know that a current creates a magnetic field and so do moving electric charges. My question is how fast a single charge moves so that it will create a magnetic field. Should its velocity be around c to make that?

Thks
 

Answers and Replies

  • #2
Meir Achuz
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A moving electron creates a magnetic field B~vXE/c.
 
  • #3
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Oh, cool, I can calculate the magnetic field of a current by this formula as well. Thanks.
 
  • #4
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This is the magnetic field generated by a moving electric charge.

[tex]\vec{B} =\frac{q \vec{v} \times \vec{r}}{r^3}[/tex]
 
  • #5
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I think that no matter how much of the charge are given, there should have a magnetic made. But whether or not it is easy to found .
is it ?
 
  • #6
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to answer haiha's question, typically in an electrical ckt, the electrons dont move around with speed of light..infact surprisingly it moves with a drift velocity. this is typically around 1cm/sec ! yes, electrons' drift velocity is very slow...it is the velocity of the signal that moves with speeds comparable to light( well it depends upon the dielectric co-effs etc). "signal" here roughly means the electro-magnetic field through space...
 
  • #7
Meir Achuz
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I think that no matter how much of the charge are given, there should have a magnetic made. But whether or not it is easy to found .
is it ?
The magnetic field of a single moving charge is a tricky calculation using Special Relativity, especially if the charge is accelerating.
 

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