B Can an expanding EM be quantized: E=mc^2?

[physicsforman]

E represent the energy of an em photon?

 

[Dale]

For a single photon E can be any value. But m will always be 0

 

[Nugatory]

E represent the energy of an em photon?

Assuming that by “em” you mean “electromagnetic”(although that’s the only kind of photon), then yes, the upper case letter $E$ is often used to represent the energy.

However, $E=mc^2$ does not apply to photons because their mass is always zero. Instead, we need the more general $E^2=(m_0c^2)^2+(pc)^2$ where $p$ is the momentum.

 

[physicsforman]

For a single photon E can be any value. But m will always be 0

Is this energy the energy of an em photon?

 

[physicsforman]

Assuming that by “em” you mean “electromagnetic”(although that’s the only kind of photon), then yes, the upper case letter $E$ is often used to represent the energy.

Does an em field expand?

 

[Nugatory]

Does an em field expand?

It’s best not to use the word “expand” at all, but instead rely on the math: do the math and you will be able to calculate the EM field everywhere and at any given time. Then you can use whatever words you want to describe the behavior, but the truth is still in the math.

Whether the word “expand” is a good description depends on the initial conditions and the source of the field. For example, if the source is a charged particle that starts oscillating, the EM field will be waves radiating outwards in all directions, and you might reasonably think of that as an expanding shell of electromagnetic radiation.

 

[physicsforman]

"It’s best not to use the word “expand” at all, but instead rely on the math:"
Lets not--does an em field physcially expand? Such as an em radio wave does it expand?

 

[Ibix]

Such as an em radio wave does it expand?

Depends what you're doing with it and how you define "expand". What scenario did you have in mind?

 

[physicsforman]

And the scenario would be----,



physics!

 

[berkeman]

And the scenario would be----drum roll, physics.

That's not helpful. When you say "expand", expand in which direction? Do you know how to write the equations for the propagation of EM waves from different sources? It would be most helpful if you could post some of that math so we have something substantive to help you with.

 

[Ibix]

View attachment 364141

Then I would say no by that definition. There's probably a fair bit of clear blue water between that dictionary definition and what you are trying to ask, though. That's why I asked for a scenario.

And the scenario would be----,
physics!

Physics is a science, not a scenario.

Do you want to stop playing stupid word games now and engage with the answers and clarifying questions you are getting? What are you imagining the radio wave doing? Where's the emitter? Is it directional? What else is around? That kind of thing.

 

[Dale]

Is this energy the energy of an em photon?

Yes. That is the only kind of photon that exists.

does an em field physcially expand?

They can (e.g. a diverging lens). They don’t always (e.g. a converging lens).

Such as an em radio wave does it expand?

Radio indicates a frequency range. You could have converging or diverging fields in that frequency range. Without a scenario there is no way to decide.

You have not provided enough information to be able to answer your question. And your manner of not providing the required information is, frankly, deliberately obnoxious. As such, this thread is closed.