# Are magnetic fields generated through radio frequencies?

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bbbl67
I seem to hear about huge astronomical events that generate radio waves seem to come from objects with huge magnetic fields, such as neutron stars and black holes. Does that mean magnetic fields only come from the radio end of the spectrum, and not higher frequencies, like IR, UV, X-rays, etc?

## Answers and Replies

Staff Emeritus
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No.

Homework Helper
Gold Member
If you mean that magnetic fields can have frequencies only up to the radio waves frequencies, that is up to say 1Ghz, then you are wrong, there are magnetic fields with higher frequencies, microwaves, IR, UV, X-rays all have at least from a classical physics point of view a magnetic field component that oscillates at their respective frequencies.

vanhees71 and Ibix
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I find this question rather confusing, and it's difficult to know how to answer other than Orodruin's response.

Electromagnetic waves include both electric and magnetic components at all frequencies, and astronomical sources often have strong magnetic fields, but these two facts aren't much related beyond the obvious "it's all electromagnetic theory". The magnetic fields may change and this may emit radiation with frequency similar to the frequency of the change. They may also concentrate and accelerate charged particles, and these may emit radiation at different frequencies.

If you want better answers you'll have to ask a better question, OP.

Last edited:
davenn, vanhees71 and Delta2
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I find this question rather confusing, and it's difficult to know how to answer other than Orodruin's response.
That is why my typical response to such questions is just
No.

berkeman, vanhees71, malawi_glenn and 1 other person
Hornbein
I seem to hear about huge astronomical events that generate radio waves seem to come from objects with huge magnetic fields, such as neutron stars and black holes. Does that mean magnetic fields only come from the radio end of the spectrum, and not higher frequencies, like IR, UV, X-rays, etc?
Magnetic fields come from relative movements of charged particles. They don't have all that much to do with radiation.

bbbl67
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Magnetic fields come from relative movements of charged particles. They don't have all that much to do with radiation.
I think you have in mind the so called static or quasi static magnetic fields. Those exist yes, but they also exist the full dynamic magnetic fields that are a component of the electromagnetic radiation of any frequency from low AC frequencies of 50hz to ultra high frequencies of gamma rays.

bbbl67
bbbl67
I think you have in mind the so called static or quasi static magnetic fields. Those exist yes, but they also exist the full dynamic magnetic fields that are a component of the electromagnetic radiation of any frequency from low AC frequencies of 50hz to ultra high frequencies of gamma rays.
So magnetic fields can produce gamma rays too?

Homework Helper
Gold Member
So magnetic fields can produce gamma rays too?
Ehm, according to classical electrodynamics if you could make a small magnet to oscillate mechanically at the frequency of gamma rays then yes you would produce gamma rays. However we can't practically make a magnet to oscillate mechanically at such gigantic frequency so we can't test this.
Besides gamma rays are fully explained not with classical electrodynamics but with quantum electrodynamics.

vanhees71
bbbl67
Ehm, according to classical physics if you could make a small magnet to oscillate mechanically at the frequency of gamma rays then yes you would produce gamma rays. However we can't practically make a magnet to oscillate mechanically at such gigantic frequency so we can't test this.
Besides gamma rays are fully explained not with classical electrodynamics but with quantum electrodynamics.
Well, what is the highest frequencies we've gotten magnetic fields to move at? You'd think something like neutron stars could produce really high speed magnetic frequencies, but they seem to be only producing radio frequencies. Have we gotten optical-frequency magnetic fields in labs somewhere?

Homework Helper
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To fully explain electromagnetic radiation in gigantic frequency such as that of gamma rays we need quantum electrodynamics theory and I am not good at that theory.
From the classical electrodynamics theory point of view a gamma ray consists of an electric and a magnetic field component that oscillate at the same frequency. However we can't produce gamma rays or x-rays or even visible light, by a mechanically oscillating magnet or by an oscillating electric current. I think maximum frequency for oscillating magnet is a few Kilohertz and maximum frequency for oscillating electric current is somewhere between 200-300 Gigahertz. Electromagnetic radiation higher than 300Ghz can be generated with other ways. Gamma rays can be generated from nuclear reactions.

bbbl67
Gold Member
2022 Award
So magnetic fields can produce gamma rays too?
As any electromagnetic radiation also ##\gamma## rays consist of electric and magnetic fields (or more precisely any time-dependent electromagnetic field has electric and magnetic field components).

Delta2
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I think there is a mini confusion here regarding what are gamma rays and how we can generate them.

bbbl67
To fully explain electromagnetic radiation in gigantic frequency such as that of gamma rays we need quantum electrodynamics theory and I am not good at that theory.
From the classical electrodynamics theory point of view a gamma ray consists of an electric and a magnetic field component that oscillate at the same frequency. However we can't produce gamma rays or x-rays or even visible light, by a mechanically oscillating magnet or by an oscillating electric current. I think maximum frequency for oscillating magnet is a few Kilohertz and maximum frequency for oscillating electric current is somewhere between 200-300 Gigahertz. Electromagnetic radiation higher than 300Ghz can be generated with other ways. Gamma rays can be generated from nuclear reactions.
No, I understand, I don't really need an explanation from QED, just wanted a confirmation about whether magnetic fields come in high energy form like which would require things like X-rays or gamma rays? So you seem to be stating that yes, indeed they do, right?

Delta2
Mentor
Well, what is the highest frequencies we've gotten magnetic fields to move at? You'd think something like neutron stars could produce really high speed magnetic frequencies, but they seem to be only producing radio frequencies. Have we gotten optical-frequency magnetic fields in labs somewhere?

Thread prefix changed to "B".

@bbbl67 -- What are your Mathmatics and Physics backgrounds, and what have you learned so far about Maxwell's equations. So far we appear to be talking past you, and not to you. We really want to help you, but that's not going to be possible until we understand your background. Thank you.

hutchphd
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No, I understand, I don't really need an explanation from QED, just wanted a confirmation about whether magnetic fields come in high energy form like which would require things like X-rays or gamma rays? So you seem to be stating that yes, indeed they do, right?
Yes magnetic fields come in high frequency, high energy form.

bbbl67
artis
To fully explain electromagnetic radiation in gigantic frequency such as that of gamma rays we need quantum electrodynamics theory and I am not good at that theory.
From the classical electrodynamics theory point of view a gamma ray consists of an electric and a magnetic field component that oscillate at the same frequency. However we can't produce gamma rays or x-rays or even visible light, by a mechanically oscillating magnet or by an oscillating electric current. I think maximum frequency for oscillating magnet is a few Kilohertz and maximum frequency for oscillating electric current is somewhere between 200-300 Gigahertz. Electromagnetic radiation higher than 300Ghz can be generated with other ways. Gamma rays can be generated from nuclear reactions.
Although everything you said is correct and I understand what you meant when you said the max frequency for oscillating currents in wires is around 300Ghz, I would like to add that currents in wires can also produce frequencies that exceed the frequency of the current itself.
One example would be a DC or low frequency AC current in a heating element or a incandescent bulb.
In theory UV from a quartz tube gas discharge lamp is also due to electrical current but the final EM is from a secondary phenomenon and not directly from the low frequency or DC current through the tube.

bbbl67 and Delta2