Electric charges moving and magnetic field

In summary, the velocity of a single charge does not have to be around the speed of light to create a magnetic field, but the calculation of the field can be complicated when considering Special Relativity and acceleration.
  • #1
haiha
136
1
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
 
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  • #2
A moving electron creates a magnetic field B~vXE/c.
 
  • #3
Oh, cool, I can calculate the magnetic field of a current by this formula as well. Thanks.
 
  • #4
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
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
to answer haiha's question, typically in an electrical ckt, the electrons don't 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
griefchan said:
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.
 

1. What is the relationship between electric charges and magnetic fields?

The movement of electric charges creates a magnetic field, and a changing magnetic field can induce an electric current. This relationship is known as electromagnetism and is described by Maxwell's equations.

2. How do electric charges move in a magnetic field?

Electric charges move in a circular or helical path when placed in a magnetic field. The direction of the movement is perpendicular to both the direction of the magnetic field and the direction of the electric current.

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

A permanent magnet is made of a material that has its own magnetic field, while an electromagnet produces a magnetic field when an electric current is passed through a wire. The strength of an electromagnet can be controlled by adjusting the amount of current flowing through the wire.

4. How are electric charges and magnetic fields used in everyday life?

Electric charges and magnetic fields are used in various technologies such as generators, motors, and speakers. They are also used in medical imaging machines, like MRI scanners, and in particle accelerators for scientific research.

5. Can magnetic fields affect human health?

There is no scientific evidence that exposure to magnetic fields from everyday objects or power lines has any harmful effects on human health. However, exposure to very strong magnetic fields, such as those found in medical devices or industrial settings, can have adverse effects on human health.

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