# Question about EM Spectrum, and EM Fields

## Recommended Posts

I'm attempting to understand their difference, and their relationship.

The Electomagnetic Specturm ranges from Gamma Waves to Long Wave Radio waves, and everything in between.

Electromagnets and other kinds of electronic equipment and power lines give off electromagentic fields.

My question is, are the electromagnetic fields emanating from electronic equipment and other electromagnetic sources, part of the Electromagnetic Specturm?

If so, what portion are they in?

If not, what is their relationship?

##### Share on other sites

It depends on their frequency. A device running at 60 Hz will be giving off radiation at 60 Hz. You need look at the frequency or wavelength scale on the spectrum.

##### Share on other sites

whenever a changing current passes through a conductor you can be certain that it is in the EM spectrum.

so yes, every electronic piece of kit that you have and use (even battery powered including your watch) is giving off signals

##### Share on other sites

whenever a changing current passes through a conductor you can be certain that it is in the EM spectrum.

So what portion(s) of the electromagentic spectrum do these electromagnetic fields lie in?

##### Share on other sites

depends on the frequency of the current.

generally at the longer wavelength side.

##### Share on other sites

So if I'm using an EMF meter to look for electromagnetic fields around my house, what portion of the electromagnetic field am I looking at?

I guess I'm having a hard time understanding the distinction between what is laid out in the electromagnetic spectrum, and what is given off in electromagnetic fields.

##### Share on other sites

any CHANGING electrical current in a conductor will give off EM radiation.

this change can be at Any rate even once a second.

the things around you home are likely to main Line frequency 50 or 60 Hz depending on your country, things like the 16KHz flyback transformer in your TV set, electric motors (frequency depends on spin rate and windings connected to the comutator) if you have Compact fluorescent bulbs then youll be getting 6 to 7 KHz broadband multi-phasic sweep etc....

theres plenty of things that make EM noise in and around the home.

##### Share on other sites

Sorry to be so difficult, just trying to understand here.

the things around you home are likely to main Line frequency 50 or 60 Hz depending on your country, things like the 16KHz flyback transformer in your TV set, electric motors (frequency depends on spin rate and windings connected to the comutator) if you have Compact fluorescent bulbs then youll be getting 6 to 7 KHz broadband multi-phasic sweep etc....

So what portion of the electromagnetic spectrum is that, is that radio waves, infrared, gamma waves, etc.?

##### Share on other sites

friends,

When ever there is an event associated with high energy electrons, there is a photon emission, so there is an electromagnetic radiation generated. Energy of the photons has something close to a normal distribution thus they form a spectrum. That's as simple as that.

check out my site: http://www.pulasthi.info

thanks

Sorry to be so difficult, just trying to understand here.

So what portion of the electromagnetic spectrum is that, is that radio waves, infrared, gamma waves, etc.?

friend,

most this at your work place or at home emmits eletromagnetic radiation in the form of heat, thus infrared waves.

check out my site: http://www.pulasthi.info

Hope you understand now:eyebrow:

##### Share on other sites

Accelerating charges radiate.... Important statement that...

Sorry to be so difficult, just trying to understand here.

So what portion of the electromagnetic spectrum is that, is that radio waves, infrared, gamma waves, etc.?

The spectrum is just a list of frequencies/wavelengths, people have named bits of it.

If you look here:

http://www.astro.virginia.edu/class/skrutskie/images/light_em_spectrum.jpg

You can see the wavelengths listed wavelength = speed of light / frequency

##### Share on other sites

most this at your work place or at home emmits eletromagnetic radiation in the form of heat, thus infrared waves.

thats utterly Useless to the OP, what he picking up is EM radiation in the Radio section for the most part (and that extends down to but not including 0Hz).

with an EMF meter most Definitely he will be "seeing" the Radio part.

IR is NOT detectable with an EMF meter I can assure!

##### Share on other sites

• 2 weeks later...
thats utterly Useless to the OP, what he picking up is EM radiation in the Radio section for the most part (and that extends down to but not including 0Hz).

with an EMF meter most Definitely he will be "seeing" the Radio part.

IR is NOT detectable with an EMF meter I can assure!

O.k. So electromagetic fields coming off of electronics and wiring, is only a certain portion of the electromagnetic spectrum?

So which portion is it?

##### Share on other sites

O.k. So electromagetic fields coming off of electronics and wiring, is only a certain portion of the electromagnetic spectrum?

So which portion is it?

It will depend on the frequency. If the oscillation is RF, you will be in the RF part of the spectrum. If the oscillation is ELF, then they will be in the ELF part of the spectrum.

##### Share on other sites

So looking at this graph:

Where is the RF and ELF portion of the spectrum located?

##### Share on other sites

see the line between Radar and Infra red?

well anything Right of that line is Radio, ELF isnt shown nor ULF but its below the AM section even or at least the lowest part of the AM section.

I will point out that although you picture is ok for showing the Visible, its not strictly accurate in it naming, AM and FM are not "Bands" they are Modes of transmission and Radar is an Application not a band either, Microwave would be better in place of Radar, UHF and VHF and some HF is better than saying "FM" or "TV", Medium wave and Longwave is better than saying "AM".

##### Share on other sites

http://en.wikipedia.org/wiki/Electromagnetic_spectrum has a more detailed breakdown, but note that the divisions are somewhat arbitrary. Different sources will have slightly different labels and cutoffs.
##### Share on other sites

yeah, that`s a Much better chart(s) and to complete it a little more: http://en.wikipedia.org/wiki/Ultra_low_frequency

and that (as far as I know) is as deep as the rabbit hole goes!

(without going into cosmological periodicity)

##### Share on other sites

O.K., so if I were looking at this graph:

What portions would I color in to represent the EMF given off by electrical gear that can be detected by an EMF Meter?

##### Share on other sites

Well mains is ~50Hz so off the bottom...

##### Share on other sites

Well mains is ~50Hz so off the bottom...

Mains, do you mean a main electrical line?

And do you mean 50MHz? Just below VHF in the Radio section?

##### Share on other sites

Yes, main electrical line, mains power is what you get from your wall sockets in most countries it's between 40 and 60Hz, and no I really do mean Hz not MHz.

##### Share on other sites

Sorry for being a dolt, I'm trying to wrap my head around these concepts in a Physics for Dummies kind of way.

But I'm having a hard time finding 50Hz on this graph:

You say it's off the bottom, below Long-Waves? By off the bottom, do you mean to say that it's not represented on the chart?

##### Share on other sites

Yeah not represented on there...

##### Share on other sites

So if that kind of EMF is not represented in that graph, would there be another graph that does represent it?

##### Share on other sites

I looked for one but they all seem to stop at around the 1km wavelength point.

## Create an account

Register a new account