# Electromagnetic Waves - Motion of Electrons/Particles/Photons and other Questions?

I have a few questions which I would like to clarify due to conflicting sources or misunderstanding.

1) As an electromagnetic wave is generated, an electric and magnetic field is created OR there is an existing electric and magnetic field in the air/atmosphere, and the produced wave is only "another" field which overrides the existing continuous fields in free space?

2) When a wave is created, what exactly 'moves' in this wave? Is it the electrons, photons or nothing is displaced (only disturbance due to energy are radiated farther away)?

3) Are the charges in the electromagnetic wave causing the radiation in free space only the positively charged particles? And if that's the case, then what is the impact of negative charges in the air/free space on this wave?

• There is one electromagnetic field, which changes over time. Sometimes it changes over time in ways that we choose to call "waves". The locations and movements of charged particles affect the field, and the field affects the movements of charged particles, but the field and the charged particles are separate things. Negative charges and positive charges affect the field in equal and opposite ways. The field pulls on charged particles much as gravity pulls on massive particles, and the field is affected by charged particles much as gravity is affected by mass. Commented Feb 6, 2017 at 5:44
• @WillO - thanks. So there is essentially one big electromagnetic field continuous in space/time, but the movement of charged particles are what impacts this EM field in a specific area/distance and time? - And the effect of charged particles creating wave, is essentially only electrons? or others as well?
– Rain
Commented Feb 6, 2017 at 5:58

Since the first question wasn't answered:

1) There exists electromagnetic field that is 0 on average. But disturbences can be induced into it that propagate outwards from the source at the speed of light. The quantum of that disturbance's power is called a photon that can do work when the wave's energy is used to do work. It's very confusing to imagine this things because of particle-wave duality though.

• Thanks. So the source's charged particles "create" photons which travel outwardly along EM field path inducing Electron Excitation? And the wave is just the excitation of electrons by that photon in a radio wave?
– Rain
Commented Feb 6, 2017 at 7:17
• This is correct. Commented Feb 6, 2017 at 7:23

2) ony an electromagnetic disturbance propagates.

3) generally radiation is caused due to electronic transmission in atoms the +ly charged nucleus usually doesn't take part in radiation. but an accelerated + charge can also produce radiation only its electric and magnetic vectors will just be opposite of -ve charge..

• Thanks, So in essence, particles/photons/electrons do not travel along the wave path, and it is only the energy transferred which makes each electron jump orbits - Is this the correct understanding?
– Rain
Commented Feb 6, 2017 at 6:15
• well photons do travell they r called "energy particle" they r quiet different from electron nd protons. i.e. photon is the energy carier...... Commented Feb 6, 2017 at 6:32
• Therefore the only particle travelling is indeed the Photon carrying energy to electrons causing the wave disturbance in the EM field?
– Rain
Commented Feb 6, 2017 at 6:35
• yup....but remember light don't need a medium to travell even in vacuum the disturbance can propagate Commented Feb 6, 2017 at 6:41
• Thanks. This is in reference to Radio Waves... which also have photons, and from your answer I'm assuming that the photons are the particles which travel and excite electrons along the path.
– Rain
Commented Feb 6, 2017 at 6:58