why isn't light bent by magnets?

[bwanaaa]

If light is an electroMAGNETiC wave, wy can i not refract or bend it with magnets?

as a corrolary to this, if one is considering laser light, why don't the magnetic fields of the photons interact to cause spreading or bunching?

 

[Calin]

Photons have no electric charge, and in their movement they are not affected by neither electric nor magnetic fields.

 

[paadness]

If photons don't have any charge, how do u make current to flow in a photo cell?

Its too difficult to even imagine light bending by magnetic field. The pattern would be impossible to create.

 

[Gibsons]

Originally posted by: paadness
If photons don't have any charge, how do u make current to flow in a photo cell?

Its too difficult to even imagine light bending by magnetic field. The pattern would be impossible to create.

Text

 

[MobiusPizza]

Photocell creates current by the photoelectric emission. When a photon hits the atomic layer of the photo cell, electron is knocked by the photon and is given sufficient energy to escape the vincity of the atomic attraction. This is called the photoelectric effect. It is NOT because the photon is charged so there's a current. It's the electrons which gained energy from the photon gave rise to the current.

 

[MobiusPizza]

The interesting point on why they are named electromagnetic wave:
All electromagnetic waves consist of electric and magnetic fields which oscillate at right angles to each other and to the direction in which the wave is travelling. They probably cancels each other out in terms of charge and magnetism so light remains neutral can clean

 

[bwanaaa]

Help me understand how magnetic fields cancel each other out. True, the divergence (del dot F) equals zero. On an intuitive level, A magnet itself has negative and positive poles - and by your analysis the opposite fields cancel each other out. However, a magnet is not impartial to a neighboring magnetic field!

So, why can I not focus light with a magnet.?

 

[f95toli]

The electric and magnetic wave does not cancel, they just travel together. Strictly speaking you can also have "pure" magnetic /electric waves (modes, in e.g. waveguides).

The photon is the exchange particle for the electromagnetic force; this means that when two magnets interact they do so by interchanging (virtual) photons.
However, this does NOT mean that photons are affected by magnetic fields simply because photons themselves are not affected by electromagnetic fields (i.e. photons are "insensitive" to other photons).

Stricly speaking it is not entirely correct to speak of photons when you talk about "ordinary" electromagnetic fields as described by the Maxwell equations, photons appear when you quantize the EM field (using the formalism of quantum mechanics) and when this is done properly these "inconsistencies" dissapear.

 

[Smilin]

Originally posted by: bwanaaa
So, why can I not focus light with a magnet.?

As was already explained, photons, or light do not have a charge and are not affected by magnets.

Same reason why you can't stick a magnet to wood. It's not charged.

If for some reason you *could* do this it would make for some very interesting applications. We already refined the technology of focusing beams with magnets in our TVs

 

[DrPizza]

Originally posted by: Smilin

Originally posted by: bwanaaa
So, why can I not focus light with a magnet.?

As was already explained, photons, or light do not have a charge and are not affected by magnets.

Same reason why you can't stick a magnet to wood. It's not charged.

If for some reason you *could* do this it would make for some very interesting applications. We already refined the technology of focusing beams with magnets in our TVs

Actually, (just a hunch here), I believe wood is probably repelled by magnetic fields (as is water.)

Also, it's not a question of the wood being "charged"
If I have a balloon with a static charge on it, it will be attracted to the wood...
A big hunk of steel may not be "charged" - it can be neutral, but a magnet sticks to the steel...

 

[bwanaaa]

Originally posted by: f95toli

However, this does NOT mean that photons are affected by magnetic fields simply because photons themselves are not affected by electromagnetic fields (i.e. photons are "insensitive" to other photons).

what?!

Please rephrase.

My interpretation of that syllogism is that photons cannot interact, For example, you cannot deflect a light beam with another light beam. is that what you mean?

It is indeed paradoxical that a wave born of (by?) electricity and magnetism cannot be disturbed by it. Why do we call it electromagnetic radiation?

 

[f95toli]

Exactly.

In the Maxwell formulation there is no "radiation", instead the mathamatical concept of a "field" is used without explicitly specifying what this field "consists" of; an electromagnetic wave is just a traveling combination of the field that surrounds e.g. a permanent magnet and the electric field around a static charge (the reason why it can propagate is because the electric- and magnetic component interacts in a specific way).

It was not until the concept of the photon was introduced much later that we started thinking of the electromagnetic field (and propagating waves) in terms of photons (and radiation, although the terms is usually only used for electromagnetic waves; not static fields).
It is possible to discuss all electromagnetic phenomena in terms of photons but unfortunately the physics gets very complicated.

 

[silverpig]

To split hairs, I'm pretty sure photons are actually attracted by all magnetic fields, but the effect is extremely tiny. The reason is because you have to modify the stress-energy tensor in GR for a charged object. If said object is spinning, it will produce a magnetic field, and this stress energy tensor curves space, gravitating the photon towards the body. But this is a bit of a stretch to say that magnetic fields attract photons though. It's more like the energy contained in the magnetic field gravitationally attracts the photon.

 

[iwantanewcomputer]

actually photons are travelling waves in both electric and magnetic fields. an existing field does not affect the direction of oscillations through it

 

[Heisenberg]

Light can be affected by magnetic fields. The Faraday, Voigt, and Cotton-Mouton Effects are all examples, although none of these effects "bend" light.

 

[f95toli]

Originally posted by: Heisenberg
Light can be affected by magnetic fields. The Faraday, Voigt, and Cotton-Mouton Effects are all examples, although none of these effects "bend" light.

AFAIK these are just magnetic analouges to the electric Kerr effect, what changes are the optical properties of the medium; the field does not affect the light directly.

 

[Heisenberg]

Originally posted by: f95toli

Originally posted by: Heisenberg
Light can be affected by magnetic fields. The Faraday, Voigt, and Cotton-Mouton Effects are all examples, although none of these effects "bend" light.

AFAIK these are just magnetic analouges to the electric Kerr effect, what changes are the optical properties of the medium; the field does not affect the light directly.

IIRC Faraday rotation can also be caused by free electrons in a magnetic field, so I guess it depends on how you classify "effect directly". But yeah, the other two are changes in the optical properties of the medium.

 

[Smilin]

Originally posted by: DrPizza
Actually, (just a hunch here), I believe wood is probably repelled by magnetic fields (as is water.)

Don't get carried away here. It was a macroscopic example. A fridge magnet doesn't stick to a 2x4.

 

[monon]

light is itself a field. this means that the occilating electric , magnetic field is all there is in light . we know that fields are not effected fields, but field effects the object producing another field. for example when electron accelerates in the presence of a magnetic field the EMW produced by the electon is not affected but the electron is effected. another example is when two charged placed near each other the electric field produced by them is effected but the charge experiences a force by the electric field produced by the other.

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Thread re-opened for non-trolling, on topic comments only.

Perknose
Forum Director

 

[ctbaars]

http://en.wikipedia.org/wiki/Isolator_(microwave)
Waveguide isolators/circulators are good examples of bending light with magnets.

 

[MrDudeMan]

http://en.wikipedia.org/wiki/Isolator_(microwave)
Waveguide isolators/circulators are good examples of bending light with magnets.

Care to explain? That isn't immediately obvious to me based on the wiki explanation.

 

[polarmystery]

http://en.wikipedia.org/wiki/Isolator_(microwave)
Waveguide isolators/circulators are good examples of bending light with magnets.

Light (photons) is not RF (high energy / frequency e & m fields) ...

 

[Z15CAM]

Light (Photons) may not be bent by magnets but it is bent by Atmospheric Prism Effects and Masses of Celestial Objects such as: the Sun, Earth, Moon and Black Holes ... etc.

The presence and mapping of Dark Matter in the Cosmos is determined by the Bending of Light around Invisible Matter.

 

[ctbaars]

Light (photons) is not RF (high energy / frequency e & m fields) ...

Sure it is ... Light is typically viewed as visible EM. Pun intended. But really light includes RF and any other band.

 

[WhoBeDaPlaya]

Light can be affected by magnetic fields. The Faraday, Voigt, and Cotton-Mouton Effects are all examples, although none of these effects "bend" light.

You're forgetting my favorite - Zeeman effect.
Love magneto-optics - was my area of doctoral research