Understanding Light: Electric and Magnetic Fields Explained

[sameeralord]

Hello guys,

Ok I read that light is an electro magnetic wave, but I don't understand what an electro magnetic wave is? I read wiki and seen diagrams but I don't get it. What do they mean light has an electric component, do they mean light is charged particles travelling, why does electric field create magnetic field? What is a magnetic field? Thanks

 

[cragar]

light is an excitation of the EM field . Light is neutral it has no charge and a zero dipole moment. If i have a proton which has a dipole moment and charge if I accelerate it , it will radiate photons , I don't know if this is what your looking for.

 

[sameeralord]

light is an excitation of the EM field . Light is neutral it has no charge and a zero dipole moment. If i have a proton which has a dipole moment and charge if I accelerate it , it will radiate photons , I don't know if this is what your looking for.

Thanks for the response I know how a photon is released from an atom. Why did you say it is accelerating? How is it constantly acted upon by a force?

 

[cragar]

if we move a proton it will emit light , i am not sure if we have to accelerate the proton
of that it just has to be moving. we could accelerate a proton with an electric field .

 

[sameeralord]

if we move a proton it will emit light , i am not sure if we have to accelerate the proton
of that it just has to be moving. we could accelerate a proton with an electric field .

Thanks again. Ok so if light is a bunch of neutral charged photons moving, then why is it called electro magnetic wave? Where is the electric component?

 

[cragar]

I don’t really know the answer to your question , But an EM wave is a self sustaining electromagnetic field , I think Maxwell wondered if a an electric field can create a magnetic field then could that create another E field an so on ,
And one of the solutions to Maxwell’s equations is
c=1/sqrt(eb)
where e= electrical constant and b is the magnetic constant
he found that these EM waves traveled at the speed of light and he knew this was no coincidence and then he realized the must be related.
Hope fully some one with more expertise will jump in an answer your question.

 

[jtbell]

Electromagnetic radiation is produced by accelerating / oscillating electric charges, but it does not itself carry electric charge. After all, you don't become electically charged simply by standing in the sunlight, do you?

Similarly, you produce sound waves by vibrating your vocal cords, but you don't have little bits of flesh from your throat flying through the air.

 

[Dale]

Similarly, you produce sound waves by vibrating your vocal cords, but you don't have little bits of flesh from your throat flying through the air.

yuck!

To the OP, it seems like you need to learn the very basics about Maxwell's equations. I would recommend starting with the Hyperphysics page:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/maxeq.html

Be sure to follow the links to each of the different laws.

 

[sameeralord]

Electromagnetic radiation is produced by accelerating / oscillating electric charges, but it does not itself carry electric charge. After all, you don't become electically charged simply by standing in the sunlight, do you?

Similarly, you produce sound waves by vibrating your vocal cords, but you don't have little bits of flesh from your throat flying through the air.

Thanks for the response So what I'm thinking is light is like an electric field between oscillating positive and negative charges. if electrons in the sun oscillate and send a light wave, what is the positive charge that the electric field runs up to?

@Dalespam: Thanks for the link I'm not studying this area, this is just for interest.

 

[HallsofIvy]

No! A magnetic-electric field itself does not have "charge", it is the field around a charged object.

Also, in earlier post you seemed to be confusing "proton" and "photon". A proton has charge and accelerates. A photon does not have charge and never accelerates or decelerates- it is always moving at speed c.

 

[sameeralord]

No! A magnetic-electric field itself does not have "charge", it is the field around a charged object.

Also, in earlier post you seemed to be confusing "proton" and "photon". A proton has charge and accelerates. A photon does not have charge and never accelerates or decelerates- it is always moving at speed c.

Thank you for your reply Ok now I understand that light is an electric field between charged particles that oscillate. So if a light ray from sun travels to earth. What are the charged particles involved to create the field? Charged particles on the sun and earth. Thanks!

Edit: I also don't understand why light doesn't need a medium to travel. In a vacuum there are no charged particles so how can light travel?

 

[cragar]

If light is emitted by fields of charged particles , then from what field does a photon come from in an anti-neutrino neutrino collision.

 

[Dale]

@Dalespam: Thanks for the link I'm not studying this area, this is just for interest.

If you are interested enough to ask the question on Physics Forums then you are interested enough to read the answer on Hyper Physics.

 

[cragar]

Electromagnetic radiation is produced by accelerating / oscillating electric charges,

I am curious then what causes the photon emission in a neutron anti-neutron
collisions , from what EM field are they created .

 

[ronaldoshaky]

An electromagnetic wave has an E field and a B which are perpendicular to each other. But other descriptions explain light as a stream of photons.

How do you marry a particle description with a wave description? Thats a question I would certainly like answered.