Explain me what is a electromagnetic wave?

In summary: The Magnetic field is a result of the Electric field and the Electric field is the cause of the Magnetic field.Basically, the Electric field is the cause of the Magnetic field, and the Magnetic field is the cause of the Electric field. This is why we call the force Electromagnetic and the theory Electromagnetic theory, not just Electric theory.In summary, an electromagnetic wave is a self-reinforcing oscillation of electric and magnetic fields that propagate through a vacuum at the speed of light. It is made up of two components, an electric field and a magnetic field, that oscillate in two planes orthogonal to each other and to the direction of the wave's propagation. The distinction between electric and magnetic fields is man-made and can be explained through
  • #1
benzun_1999
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0
Dear reader,
can any on explain me what is a electromagnetic wave?

-benzun
please go easy with me
 
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  • #2
It is a self-reinforcing oscillation of the electric and magnetic fields that propagates through a vacuum at the speed of light, c.

A changing electric field creates a magnetic field, and a changing magnetic field creates an electric field -- therefore, when both fields are changing, they are self-reinforcing. Specifically, the two fields oscillate in two planes orthogonal to each other and to the direction of the wave's propagation.

- Warren
 
  • #3
The basic descriptor for this class of wave is "transverse wave". As stated by Warren, EM waves have two components that are at 90 degrees to each other and the action of these components are transverse to the direction of the wave, as opposed to "longitudinal waves". See the discussion at the following URL:

http://www.physicsclassroom.com/Class/waves/U10L2a.html
 
  • #4
Whats the difference between an electric and a magnetic field?

Please explain in detail, or show the difference if that is possible.
 
  • #5
Electric fields are caused by charge. Electric fields apply force to a positive charge in the direction of the field. Electric fields are conservative (If you move a charge around and get back to where you started from, no work is done) and thus have a scalar field associated with it called the electric potential (Usually denoted V).

Magnetic fields are caused by moving charge. Magnetic fields apply force to moving charges perpendicular to the direction of the field and the motion of the charge. Thus Magnetic fields are non conservative and do not have a scalar potential associated with them. Magnetic fields have a vector potential instead, however it has no physical significance, it is more a mathematical conveniance.

Changing electric fields generate magentic fields and vice versa. Thus an electromagnetic field can be self propagating as explained by chroot.

That's all I can rattle off on the top of my head, for more information, do a web search or look up 'Introduction to Electrodynamics' by Griffiths.

Claude.
 
  • #6
I believe that the only true answer to this is simply, none. A person stationary with respect to a electric charge sees an electric field, a person moving wrt to the same charge sees a magnetic field. All that changes is the velocity of the observer, same charge, same field.
 
  • #7
Integral is correct, the distinction we make between Electric and Magnetic fields is purely man made.

This is an important point, one that I probably should have made in my previous post.

Claude.
 
  • #8
Integral is correct, the distinction we make between Electric and Magnetic fields is purely man made.
True! But it is even stronger. A magnetic field simply does not exist. Magnetic forces are seeming forces. In a weak analogy it is like the coriolis force: There is a force, but in fact something different than assumed at the first glance.

The origin of magnetism is: If you observe a collection of moving electric charges from a moving position, you will - by relativistic causes - see those charges contracted; but some of the charges more contracted than the others. This causes a resulting force even if the total summary of all charges is zero. This is magnetism.

You will find a short explanation of in in P. French: Special Relativity. You will find it in detail in Rosser: Electromagnetism by Special Relativity (Butterworth, London)
 
  • #9
Albrecht

Please expand on:
by relativistic causes - see those charges contracted;

Thanks
 
  • #10
magnetism

Assume you have a wire with an electric current in it. The electric current can be understood as a chain of positive electric charges into one direction and a chain of negative charges into the other one.

Both chains shall have the same density and move at the same velocity.

A test charge (assume a negative one) at rest will see a neutral electric field. It will see both chains a bit contracted due to relativity. (Special relativity states that every object in motion is contracted.) Contraction is the same for both.

If now the negative test charge is moved in the same direction as the negative chain, i.e. parallel to it, this test charge will see the negative charges less contracted than before and the positive charges more contracted than before. So it will, in a summary, see a positive charge in the wire, and it will be attracted to the wire.

An observer at rest, who does not see this non-balance, will assume a new force which by tradition has the name: "magnetic force".
 
  • #11
On most illustrations you see the electric wave and magnetic wave are "in sync". Aren't they really 90 degrees phase dislocated to each other?
 
  • #12
Originally posted by AndersHermansson
On most illustrations you see the electric wave and magnetic wave are "in sync". Aren't they really 90 degrees phase dislocated to each other?

Look up at the corner of your room. The Electric field varies on one wall, the Magnetic field on the other. In this case the direction of motion is toward the floor or ceiling.

When the Electric field is at an absolute maximum value on its wall the Magnetic field is at an absolute minimum value (at zero) on the other.

When viewed Relativistically it becomes clear that the Magnetic and Electric fields are different manifestations of the same phenomena.
 

1. What exactly is an electromagnetic wave?

An electromagnetic wave is a type of energy that is made up of oscillating electric and magnetic fields. These waves are created by the acceleration of charged particles and can travel through a vacuum. They are responsible for a vast range of phenomena, from radio waves and visible light to X-rays and gamma rays.

2. How do electromagnetic waves differ from other types of waves?

Unlike mechanical waves, such as sound waves, electromagnetic waves do not require a medium to travel through. They can travel through a vacuum, which is an empty space with no physical matter. They also differ from sound waves in that they can travel at the speed of light.

3. What are the different types of electromagnetic waves?

Electromagnetic waves are classified into seven categories based on their wavelengths and frequencies: radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. These waves have varying frequencies and energies, with radio waves having the lowest frequency and energy, and gamma rays having the highest.

4. How are electromagnetic waves used in everyday life?

Electromagnetic waves have many practical applications in our daily lives. Some common examples include using radio waves for communication, microwaves for cooking, infrared waves for remote controls, visible light for vision, and X-rays for medical imaging. They are also used in technologies such as radar, satellite communication, and wireless internet.

5. How are electromagnetic waves related to the electromagnetic spectrum?

The electromagnetic spectrum is a range of all possible electromagnetic waves, sorted by their frequencies and wavelengths. Electromagnetic waves are directly related to the electromagnetic spectrum, as they differ in frequency and wavelength, but all fall under the same category of energy. This spectrum includes all types of electromagnetic waves, from radio waves with the longest wavelengths to gamma rays with the shortest wavelengths.

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