# Which part of the light wave do we take? (quick question)

## Main Question or Discussion Point

Hello,

Quick question. This is a light wave

This is another light wave

Why doesn't this graph have another perpendicular graph. Are they talking about the particles in the magnetic field or electric field here or both.

Simply how do they make one wave out of a light wave that has two waves.

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Doc Al
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Why doesn't this graph have another perpendicular graph. Are they talking about the particles in the magnetic field or electric field here or both.
While your first diagram seems like the usual depiction of an EM wave (which is what light is, classically), it's not clear what that second diagram is supposed to show. (It looks like it's meant to depict the force on some charged particle.)
Simply how do they make one wave out of a light wave that has two waves.
A light wave has both electric and magnetic fields, which are at right angles to each other. But that doesn't mean you always have to show both in a diagram.

While your first diagram seems like the usual depiction of an EM wave (which is what light is, classically), it's not clear what that second diagram is supposed to show.

A light wave has both electric and magnetic fields, which are at right angles to each other. But that doesn't mean you always have to show both in a diagram.
Thanks Doc Al!! So most of the time I think they show the electric field. When light has a particular freuqency would both electric and magnetic waves travel at that frequency. I think they do because one is created from the other.

Doc Al
Mentor
When light has a particular freuqency would both electric and magnetic waves travel at that frequency.
Yes.

Yes.
Thanks Doc Al Topic closed unless someone wants to start the topic if light is a wave or particle

Thanks Doc Al!! So most of the time I think they show the electric field. When light has a particular freuqency would both electric and magnetic waves travel at that frequency. I think they do because one is created from the other.
Wrong. Electric and Magnetic fields in EM waves DO NOT "create each other". Sorry Wikipedia is wrong on that. (and they won't correct it, because they are determined to keep it wrong) Electric and Magnetic fields of waves are both created by the source of the waves (moving charges) not each other.