[Q] Light and magnets

[n00b]

If light is part of the electromagnetic spectrum, does this mean that light can be influenced by strong magnetic fields?

[Moontanman]

No, light is not affected by magnetic feilds.

[Essay]

Gee, why not? :D

...but I guess electric fields don't affect light either. :shrug:

 

Hey! :hyper:

 

Light propagation is characterized by alternating electric and magnetic fields ...or something like that, right?

 

Electric and magnetic components are perpendicular to each other, with sine wave ...nature.

 

Are the electric and magnetic peaks in phase with each other?

 

Yes, of course they are (well I'll assume....) ;)

 

So my problem is that I picture a field as 3 dimensional, say like a doughnut or....

...but then why doesn't it overlap with the magnetic 3-D field...?

 

I guess I need to learn more about what polarization detects....

...the orientation of the fields, not the fields themselves....

 

hmmmm. Any comments, thoughts, guidance, suggestions, opinions, etc.?

 

...but then why don't other magnetic fields affect light? Is is just one dimension of a magnetic field that is being propagated, or a whole 3-D field? :)

 

~ :hihi:

[CraigD]

Described in terms of particles, both light and magnetic fields are made of photons. In their role as carriers of magnetic force, photons can affect only particles with non-zero charge. Photons have zero charge, so can’t be effected by the magnetic force they carry – in other words, photons can’t affect one another’s momentum.

 

Force carriers – bosons - are essentially momentum carriers. In addition to their role as magnetic force carriers, photons carry momentum in their role as radiation. The most common example of photons in this role is in carrying momentum from electrons in glowing atoms, which then change to a lower energy orbital, to electrons that absorb them, changing to higher energy orbitals, or separating – ionizing – them from their atoms altogether.

 

There’s an important, difficult to explain difference between the formal nature of photons as magnetic force and as light, which is too involved to explore in detail in a Q&A thread. To explore more, browse information about virtual particles. In the role of magnetic force carrier, photons are virtual. In their role as radiation, they are not.

[Karnuvap]

No, light is not affected by magnetic feilds.

 

Except ....

 

 

When you reflect polarised light off the polished pole of an electro magnet the polarisation is changed if the magnet is energised.

 

See also the way that satellite dish's LNB's use a coil to affect the polarisation of the signal they receive - not visible light but electromagnetic waves of a different frequency.

 

Not quite the bending of light waves by magnets but a magnetic effect on electromagnetism nonetheless.

 

Karnuvap

[CraigD]

Moderation note: Additional discussion of this question was moved to 17796, because is is more of an in-depth discussion of physics than simple question & answer

[logy]

Gee, why not? :D

...but I guess electric fields don't affect light either. :shrug:

 

hmm, seems that 'why' is a bit of a tricky question so instead i will try to focus on 'what';

particles affect other particles via fields and waves.

light waves are not affected by fields.

 

(waves which are cosidered particles in quantum mechanics, but are fundamentally different from 'normal' particles as they have zero rest mass)

(waves are cuved by gravity according to general relativity, but that is a result of the curvature of space-time, rather then a force acting on a particle)

 

Light propagation is characterized by alternating electric and magnetic fields ...or something like that, right? yes that is persisely right.

 

Electric and magnetic components are perpendicular to each other, with sine wave ...nature. once again percicely right :)

Are the electric and magnetic peaks in phase with each other? yes

 

Yes, of course they are (well I'll assume....) :naughty:

 

So my problem is that I picture a field as 3 dimensional, say like a doughnut or....

an electric field is 3-D and a simple representation such a field that is generated by a positive point charge can be found here http://www.geocities.com/rmazzio/U6ExamImage1.gif

a magnetic fiels is also 3-D but is a bit more tricky since it has a south and north pole it looks like this:

http://www.magnetic-shield.com/images/faq/flux-images.jpg

...but then why doesn't it overlap with the magnetic 3-D field...?

it does overlap, and as a result the changing magnetic field generates the electric field and visa versa

I guess I need to learn more about what polarization detects....

...the orientation of the fields, not the fields themselves....

polarization is interesting, but not nessesary in order to understand light. a good 3-D representation of light's elecrtic and magnetic fields can be found here.

File:Onde electromagnetique.svg - Wikipedia, the free encyclopedia

hmmmm. Any comments, thoughts, guidance, suggestions, opinions, etc.?

 

...but then why don't other magnetic fields affect light? Is is just one dimension of a magnetic field that is being propagated, or a whole 3-D field? :evil:

umm this is a bit of a tricky one. perhaps you can try to work out *how* electric and magnetic fields affect charged particles, then you will see that the rules cannot be applied to light

i hope this will make thigs a bit less confusing