Electromagnetic wave /Field question

In summary, there is a difference between electromagnetic waves and fields, as fields are defined at every point in space while waves involve a propagation. In a varying field, electric and magnetic fields are coupled together. It is possible to have an electromagnetic wave with only a magnetic or electric field, but they will still be coupled together.
  • #1
zak8000
74
0
Hi

i was wondering what's is the difference between electromagnetic waves and fields or is a field just a number of electromagnetic waves. also i was wondering is it possbile to have an electromagnetic wave where there is only a magnetic field and no electric field and vice versa

Thanks
 
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  • #2
Good questions.

First, you can have a steady dc electric field or a magnetic field, without the other. This is true even if the dc field varies in space.

If either the magnetic field or the electric field is varying with time, then you have to have the other field also, because the two varying fields are coupled by Maxwell's equations.

Bob S
 
  • #3
zak8000 said:
Hi

i was wondering what's is the difference between electromagnetic waves and fields or is a field just a number of electromagnetic waves. also i was wondering is it possbile to have an electromagnetic wave where there is only a magnetic field and no electric field and vice versa

Thanks

This is a good question, both electric and magnetic field are vector fields which is a point form. By point form, it means the amplitude and the direction is defined at every point in space.

By definition of EM wave, it is a varying field where Bob S answered already that in a varying field, E and M and coupled together by Maxwell's equations.

BUT on top of all the above, there is a propagation of the EM wave that I am not absolute sure. I believe it is still a vector field at every point in space, it just vary in the direction that "looks" like as if it is moving.

Remember the explanation of water wave with a floating balls? The over all wave looks like it is moving in a certain direction, but if you throw a bunch of floating balls into the water wave, they only bobble up and down vertically! With this, I would say the EM wave is a vector field that "bobble" is a stationary point.

Someone with more authority might want to jump into confirm this. I am still learning.
 
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FAQ: Electromagnetic wave /Field question

1. What is an electromagnetic wave?

An electromagnetic wave is a type of energy that is produced by the acceleration of electric charges. It is characterized by its oscillating electric and magnetic fields that are perpendicular to each other and to the direction of the wave's propagation.

2. How are electromagnetic waves created?

Electromagnetic waves are created when an electric charge is accelerated or oscillated. This can happen naturally, such as when lightning occurs, or it can be artificially generated through devices like antennas or lasers.

3. What is the difference between an electromagnetic wave and an electromagnetic field?

An electromagnetic wave is a form of energy that is produced by an electromagnetic field. The electromagnetic field is a region of space where the electric and magnetic fields are present, even in the absence of an electromagnetic wave.

4. What are the properties of electromagnetic waves?

Electromagnetic waves have several key properties, including wavelength, frequency, and speed. They also have the ability to travel through a vacuum, and they can be polarized, meaning their electric and magnetic fields can be oriented in a specific direction.

5. What are the practical applications of electromagnetic waves?

Electromagnetic waves have countless practical applications in our daily lives. Some common examples include radio and TV broadcasting, wireless communication, radar technology, and medical imaging. They are also used in industrial processes, such as heating and welding, and in scientific research, such as spectroscopy.

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