# Light & Electromagnetic fields

TheShapeOfTime
Is the light we see just wave of a certain frequency in an electromagnetic field?

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## Answers and Replies

Doc Al
Mentor
Visible light comprises a range of frequencies (or wavelengths) of electromagnetic waves. In terms of wavelength, the visible spectrum extends roughly from about 400nm (blue/violet) to 700nm (red). "White" light is a mix of all visible wavelengths.

TheShapeOfTime
This may be a dumb question, but where does the electromagnetic field come from? Would it make sense to ask if it's everywhere?

See, there's this experiment where its shown that a moving electron creates a electromagnetic field that travels perpendicularly from the position of the electron at that moment. That is the same basis on which we have our wireless communication.

Now, the light we get from stars is the result of the combining of helium nuclie, they generate energy and also some light. In tubelights and other such sources, the gas inside the tube gets heated up which results in the creation of light. In a bulb, the tungsten filament that creats light by getting heated up.

See, wherever there is light, there is heat, or vice versa. So, basically, when stuff getz heated up, the electron jumps orbits and gets exited and this results in the creation of light.

Let there be light and there was light!

P.S.
Other's please feel free to correct me if i'm wrong, which is probable.

Integral
Staff Emeritus
Science Advisor
Gold Member
Thinker,
You need to do a bit more reading, and bit less posting about this topic. You have pretty much missed the mark.

The energy for light comes from the electron shell of atoms. Each time an electron moves from a high energy state to a lower energy state, that change in energy becomes a photon of electro magnetic energy. The energy of the photon, thus the color, is the same as the energy change of the electron in the atomic shell structure. Likewise, a photon can be adsorbed by the electronic shell structure of an atom, this causes an electron to move from a low energy state to a higher energy.

TheShapeofTime,

If I am reading you, then you are asking if light is like a disturbance of some pervasive electromagnetic field, like dropping a rock into a pond of water creates waves on the surface of the pond.

About a century ago, people were debating if light traveled through the "ether", a mysterious and undetected substance that filled all space. When experiments like those done by Michelson and Morley showed that the speed of light was invariant with respect to moving at different velocities through the hypothesized ether, people had to give up on the idea.

Light is an electromagnetic field that moves through space. You can have a completely empty region of space, no matter and no fields, and light will travel right across it, and leave nothing behind.

What happens is that somewhere there is a changing electric or magnetic field. As described by Maxwell's equations, this changing field in turn creates a changing magnetic or electric field in the adjacent region of space. This in turn creates a changing electric or magnetic field.... hopefully, you get the idea. The frequency of a light wave is just how many times in a second that the electric or magnetic field in the light wave cycles back to its original value.

Electrons are the usual suspects for light production. Besides hopping around in atoms or molecules (transitions between different quantum states/energy levels), electrons can radiate light through plain old acceleration. When you bend the path of a moving electron with a magnetic field, you accelerate the electron and get something called synchnotron radiation, which is just light. This is a problem if you are a particle physicist who wants a powerful electron beam, but is very handy if you are a solid state physicist who wants a powerful source of x-rays.

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