Quantum, photon, wavelength relationship

Main Question or Discussion Point

Hi Guys,
Is there a SIMPLE (I am not a physicist) relationship between a quantum of energy, the photon(s) involved and the wavelength (or frequency) of the photon(s) involved in making up of the quantum?
Regards.
Pierre

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Hi,
I guess you are looking for Planck's formula.

bapowell
Planck's formula:

$$E = \frac{hc}{\lambda}$$

where h is Planck's constant, c is the speed of light, $\lambda$ is the wavelength, and E is the energy of the photon. The photon is the quantum of the electromagnetic field.

Hi Bapowell,
Thanks for the response. I guess what I need to know is the relationship between a quantum of energy and a photon. Is there a relationship?
Regards.
Pierre

f95toli
Gold Member
A photon IS -more or less- a "quantum of energy".

Thanks for that definition ... more or less is OK for me. The fact that we are dividing by the wavelength makes this quantum of energy by definition always one wavelength long. Is that correct?

bapowell
Thanks for that definition ... more or less is OK for me. The fact that we are dividing by the wavelength makes this quantum of energy by definition always one wavelength long. Is that correct?
Not necessarily -- it's just a function of $\lambda$. The size of a photon is not known and is a tricky theoretical concept. As a particle, it is a zero-dimensional point. But it has a wavefunction, and this gives it a sense of spatial extent. A photon is a quantum of energy of the electromagnetic force. It is not correct to think of the photon as any more general than that. Of course, in most problems of interest in introductory physics (electrons jumping energy levels and emitting quanta) the electromagnetic force is the main player.

Hi Bapowell,
Thanks for the response. My dilemma is that I am trying to get my head around the type of emission one could expect from primordial particles. Being so small, their would their ability to absorb and then emit more than one quantum at a time be limited or could you expect a continuous wave from such a small thing?

bapowell
Hi Bapowell,
Thanks for the response. My dilemma is that I am trying to get my head around the type of emission one could expect from primordial particles. Being so small, their would their ability to absorb and then emit more than one quantum at a time be limited or could you expect a continuous wave from such a small thing?
I would need to know more details about what you are trying to do. What do you mean by primordial particles? What are their properties (mass, charge, spin, etc)? Are these particles free or are they interacting with each other? If they are interacting, are you considering them as occurring in bound states?

I am thinking of a theoretical situation with free particles in space, not interacting. Mainly electrons, quarks (up and down) and neutrinos.

Sir bapowell I think Its Pierre007080 's homework with which he's facing problem. (hey Pierre007080 Don't mind as I exactly don't know your problem unless u explain)

Hi Derek. Yes, this is my homework. I am 58 years old and am trying to do some original thinking with regards to dark matter. In my hypothesis I see dark matter as primordial particles being formed continuously. I am trying to ascertain the type of emission that such dark matter would produce. Is it single photons being emitted or is it a continuous wave. Would it be in the microwave region? Is it maybe CMB?

bapowell
Hi Derek. Yes, this is my homework. I am 58 years old and am trying to do some original thinking with regards to dark matter. In my hypothesis I see dark matter as primordial particles being formed continuously. I am trying to ascertain the type of emission that such dark matter would produce. Is it single photons being emitted or is it a continuous wave. Would it be in the microwave region? Is it maybe CMB?
It depends on lots of things. The fact that dark matter is 'dark' is a result of the fact that it is electromagnetically neutral -- it emits and reflects no light. Therefore, dark matter particles should not be emitting any photons whatsoever. If they did, they would have spectral properties that could be observed. As a side note, the CMB was generated 13 billion years ago approximately instantaneously. It is a near perfect blackbody with a temperature of around 2.7 Kelvin and is exceptionally uniform to 1 part in 100.000. Dark matter is clumpy as a result of its gravitation (similarly to ordinary matter) and so even if it did somehow manage to emit radiation, it would be exceedingly difficult to generate such a smooth and pristine radiation field as the CMB.

Another formulation of the photon's energy is:

E = hf

Where h is the Planck Constant and f is the frequency of the photon. In general, the frequency will be higher for photons that arise from jumps of energy that occur within smaller areas of space. If you are looking for very tiny particles you should look for extremely high frequency/high energy photons. The radiation associated with them would likely be more intense than even gamma rays.

Sorry sir Pierre007080 I wasn't knowing about your problem.
As it was because you sounded similar to my friend who was having a problem in photoelectric emission project.
I ask for apology, and please spare me as I'm new,a student and just turned 18 a couple of months ago.

Hi Bapowell,
I am concerned this debate may take us outside the rules that this forum allows with regards to alternative views from the standard model. It is for this reason that I am trying to keep my questions as basic as possible. NOTHING in the universe is at or below 0 degrees K and as such MUST emit. Perhaps we should keep the debate along the lines of my question: would such (theoretical) non-interacting particles weighing 500 000 to 8 000 000 eV emit photon by photon or a continuous wave?

Hi Guys, surely the emission frequency cannot depend upon th SIZE of the particle???

Hi Derek,
No sweat man.

bapowell
Hi Bapowell,
I am concerned this debate may take us outside the rules that this forum allows with regards to alternative views from the standard model. It is for this reason that I am trying to keep my questions as basic as possible. NOTHING in the universe is at or below 0 degrees K and as such MUST emit. Perhaps we should keep the debate along the lines of my question: would such (theoretical) non-interacting particles weighing 500 000 to 8 000 000 eV emit photon by photon or a continuous wave?
If they are non-interacting, then by this very definition they cannot emit photons.

may I take it as an 'okay' .Sir?

Hi Guys, surely the emission frequency cannot depend upon th SIZE of the particle???
Not necessarily the size of the particle, but rather the area in which the energy is bound or modulating. For visible light, it is the ratios of the before and after electron orbitals about the atom or molecule that determine the photon frequency. (Before and after radiation occurs that is)

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If they are non-interacting, then by this very definition they cannot emit photons.
When I say non-interacting, I mean in the sense of the particle binding with other particles. Any EM radiation would either destroy such small particles or be absorbed. If the energy were absorbed these tiny particles would probably emit the energy pretty promptly. It is this emission that I refer to. Single photon?

may I take it as an 'okay' .Sir?
Hi Derek,
Of course it is "okay"
Kind regards.
Pierre

Not necessarily the size of the particle, but rather the area in which the energy is bound or modulating. For visible light, it is the ratios of the before and after electron orbitals about the atom or molecule that determine the photon frequency. (Before and after radiation occurs that is)
Hi PhilDSP,
Perhaps you are referring to atoms with orbitals. These subatomic particles have weights that are on the same scale as a gamma ray photon. Is it possible that they could emit photons nearly their own weight?

bapowell