If light has no charge and mass, how can it have an electric field?

In summary: The photon is just a manifestation of the field's energy and momentum. Therefore, it does not create its own EM field. In summary, we discussed the behavior of a test charge near an electric field and how it moves in both directions. This behavior can also be observed in the ionosphere and through experiments such as "Direct measurement of light waves". The concept of a photon is closely tied to the electric field, as it is the quanta of interaction. The photon does not create its own EM field, but rather is a manifestation of it.
  • #1
jlyu002@ucr.e
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Since it does have an electric field, if we were to put a positive test charge near it, would it exhibit an inward field or an outward field?
 
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  • #2
A photon doesn't produce an electric field, it is a neutral particle as you stated in the title. Photons are the excitations of the electric field.
 
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  • #3
A test charge would move first in one direction, then the other.
 
  • #4
Vanadium 50 said:
A test charge would move first in one direction, then the other.

And it does this, frequently, up in the ionosphere - or you wouldn't hear HF transmissions from all over the World.
 
  • #5
Vanadium 50 said:
A test charge would move first in one direction, then the other.

Do you know of any video or specific experiments that show this behavior? I'm really interested.
 
  • #6
Jd0g33 said:
Do you know of any video or specific experiments that show this behavior? I'm really interested.

"Direct measurement of light waves", E. Goulielmakis et al., Science 305, 1267 (2004). http://www.attoworld.de/Documents/papers/Science/Science305p1267_2004.pdf.

These are not charges at rest moving back and forth, but you see a modulation in the kinetic energy/momentum of moving electrons, which is close enough, I guess.
 
  • #7
Jd0g33 said:
Do you know of any video or specific experiments that show this behavior? I'm really interested.

Turn on a radio. It uses this exact behavior.
 
  • #8
Jd0g33 said:
Do you know of any video or specific experiments that show this behavior? I'm really interested.

Yes. It's called a "radio antenna".
 
  • #9
Funny, now I'm curious too... can there exist a photon without some sort of external/residual/whatever of a field? I know the e and m fields balance/cancel when traveling at c... really? And apologies, holiday weekdnd, kinda been drinking.
 
  • #10
WhatIsGravity said:
Funny, now I'm curious too... can there exist a photon without some sort of external/residual/whatever of a field? I know the e and m fields balance/cancel when traveling at c... really? And apologies, holiday weekdnd, kinda been drinking.

A photon is the quanta of interaction of the EM field, so no, it cannot exist without the EM field.
 
  • #11
Drakkith said:
A photon is the quanta of interaction of the EM field, so no, it cannot exist without the EM field.

Does a photon create it's own EM field, as it goes, or is that field just there?
 
  • #12
WhatIsGravity said:
Does a photon create it's own EM field, as it goes, or is that field just there?

To my knowledge, the field always exists.
 

1. How can light have an electric field if it has no charge or mass?

While light particles, also known as photons, do not have a charge or mass, they do have energy and momentum. This energy and momentum can create an oscillating electric field, which is a fundamental property of light.

2. What is an electric field and how is it related to light?

An electric field is a region in space where electrically charged particles experience a force. Light particles, or photons, have an oscillating electric field that is created by their energy and momentum.

3. How does the electric field of light interact with matter?

The oscillating electric field of light can interact with matter through a process called electromagnetic radiation. This can cause charged particles in matter to move and create electrical currents.

4. Can light's electric field be measured or detected?

Yes, light's electric field can be measured and detected through various methods such as using a device called a polarimeter or observing the behavior of charged particles in the presence of light.

5. Is the electric field of light the same as the electric field of other charged particles?

No, the electric field of light is different from the electric field of other charged particles. While other charged particles have a constant electric field, the electric field of light oscillates at a specific frequency depending on its energy.

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