Magnetic field and an electrical field

In summary: The electric field generated by a current in a wire is perpendicular to the current and does not always point in the direction of the current. In fact, it is perpendicular to the electric field if the current is steady.
  • #1
Michael Lin
11
0
Hi all,
We know that if we have a current, we create a magnetic field and an electrical field. By the right hand rule, we can find the direction of the B, and E field. (ExB should give us the direction of the current). Now suppose we have electromagnetic induction. The B and E from before causes a local current. Is this local current still obey the E x B relation for direction?


Thanks,
Michael
 
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  • #2
Induction currents are generated by changes in magnetic flux. Magnetic flux is equal to the surface integral of B.da (<-- dot product). The direction of the new (local) current will be that which opposes a change of magnetic flux. The E and B fields created by this new current will obey all the same laws as any other situation.
 
Last edited:
  • #3
Michael Lin said:
Hi all,
We know that if we have a current, we create a magnetic field and an electrical field. By the right hand rule, we can find the direction of the B, and E field. (ExB should give us the direction of the current). Now suppose we have electromagnetic induction. The B and E from before causes a local current. Is this local current still obey the E x B relation for direction?
Thanks,
Michael
I'm a bit confused as to what electric field you're talking about.:confused:

A magnetic field that changes with time "creates" (i.e. its existence is simultaneous with) an electric field. Is that what you meant? If so then you can have a steady current creating a constant magnetic field. If you have a current carrying wire then inside the wire there is an electric field whose value is given by Ohms law. The value ExB does not always point in the direction of current flow. In fact in a straight wire with a steady current flowing in it ExB is perpendicular to the wire and hence the current. This gets into some very hairy physics and is best described by the article

Examples of Momentum Distributions in the Electromagnetic field and in Matter, W.H. Furry, Am. J. Phys., 37(6) June 1969

Pete
 

1. What is the difference between a magnetic field and an electrical field?

A magnetic field is created by moving electric charges, while an electrical field is created by stationary electric charges. Additionally, a magnetic field is perpendicular to an electrical field.

2. How are magnetic fields and electrical fields related?

Magnetic fields and electrical fields are closely related through the phenomenon of electromagnetism. When an electric current flows through a wire, it creates a magnetic field around the wire. Similarly, a changing magnetic field can induce an electric current in a wire.

3. What are the units of measurement for magnetic and electrical fields?

The SI unit for magnetic field is Tesla (T), named after the famous scientist Nikola Tesla. The SI unit for electrical field is Volt per meter (V/m).

4. How can magnetic and electrical fields be used in technology?

Magnetic and electrical fields have a wide range of applications in technology, such as in motors, generators, transformers, and speakers. They are also used in medical imaging, particle accelerators, and data storage devices.

5. Can magnetic fields and electrical fields be harmful to humans?

Exposure to high levels of magnetic and electrical fields can potentially be harmful to human health. However, the levels of these fields produced by everyday technology, such as cellphones and power lines, are well below the safety limits recommended by regulatory agencies.

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