electromagnetic spectrum

[Snake]

hello
today, a frien called me and asked me something about the elctromagnetic spectrum, and I wanted to hear what you guys think about it.

Wel so light travels by photons, and light is just one part of the electromagnetic spectrum, and the only difference between light and lets say radio waves is the wavelength. But, if you are in a dark room (shilded from the photons and hence visible light) you can still pick up a radio station (radio waves must be present).

So , the question was if radio waves, micro waves and all the other parts of the em spectrum also traveld in photons, like light? I would really want to hear what you guys think about this.

Snake

[Drosera]

Hi!

I'll try to give you a brief, understandable answer before someone gives you a response with 'many big words'.

Yes, all forms of electromagnetic radiation travels in packets called photons. A key characteristic of the various different 'kinds' of photons is their wavelength. A longer wavelength has less power than a shorter one.

If I understand properly, what differentiates one kind of EM radiation from another is the wavelength, and the way the photons are produced or react with other particles. Radio waves are produced by oscillating electric currents (correct?) and carry very little power. Light is produced through shifts in valence level of electrons. (hoping I'm still right) They carry more power, and are the only form of EM radiation our eyes can see.


Take care!

[Drip Curl Magic]

hmmm, I have another question. I've heard my mother talk about how when you turn on the stove, and it turns red.... that it has something to do with infra-red light. Is that true? and if so, how is it that the infra-red light is being made visible?

[UncleAl]

Originally Posted by Drip Curl Magic

hmmm, I have another question. I've heard my mother talk about how when you turn on the stove, and it turns red.... that it has something to do with infra-red light. Is that true? and if so, how is it that the infra-red light is being made visible?

Google Images
"blackbody curve" 37 hits

http://javalab.uoregon.edu/dcaley/prf/PRF_plugin.html

[Drip Curl Magic]

oh, wow, most of that went right over my head as I was reading it. either I need to touch up on my scientific lingo, or my brain sucks. I'm hoping it is the first one.

[Drosera]

Hello again!

Sometimes simpler explanations are better, eh?

I'm not sure if I'm completely right about what follows, so if anyone refutes me, take their word for it.

Stove burners do indeed emit infra-red radiation. I believe this is because there is alot of electrical resistance in the elements, which causes increased agitation in the molecules of the burner (ie. heat). The extra energy of the molecules can be released as IR radiation.

But the red you see is not IR radiation, but visible light radiation. Don't ask me why, but the burner is releasing 2 different radiations in this case.

FWIW, burners transfer alot more heat through conduction (touching) than through IR radiation. But I'm guessing mom already knows that.

Take care!

[GAHD]

Drosera is right, but the element's actually releasing a range of wavelenths that just happens to get closer to visible as it heats up. If it got even hotter it would cycle 'up' to orange and yellow as more green light started getting emitted, and finally white once it started releasing blue.

[Drip Curl Magic]

Originally Posted by GAHD

Drosera is right, but the element's actually releasing a range of wavelenths that just happens to get closer to visible as it heats up. If it got even hotter it would cycle 'up' to orange and yellow as more green light started getting emitted, and finally white once it started releasing blue.

ahh, so it's the same principals of the different colors that fire can emit. Thank you both for the clarification.

[arkain101]

Correct me if im wrong too.

Then you heat it up more, ultra violet, then we get some x rays.. and eventually if you get the energy you split some atoms or is it fuse them and get gamma rays.
Weird thing is though, X-rays can pass through matter quite easily, normal light cant, but so can micro waves/ radio waves. If they are all the same thing I find it confusing that cirtain frequencies have different abilities, when each and every form is a way of transporting energy from one excited mass to another.

[GAHD]

pritty much, but once it starts adding indigo and violet, then ultraviolet to the mix you start seeing a weird 'super white' color, real intense.

If you want a good explanation of EM, NASA has not just one but two different pages, and this cassini page gives a lot of the basic information too.

On different frequencies passing through different matter, in general it has to do with the densities of the mater in question vs the frequency and amplitude of the waves attempting to pass through.

Sometimes structure comes into play too: Sand is almost opaque, while glass made from that same sand is pritty much transparent.

Another big thing is how much of a refractive index the material has, sometimes it's so high that the waves are reflected right back around.

I hope that helps, I know particle physics isn't exactly the easiest subject to wrap your brain around.