###### Jonathan Osbourne

PhD., University of Maryland
Published author

Jonathan is a published author and recently completed a book on physics and applied mathematics.

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# Electromagnetic Spectrum

Jonathan Osbourne
###### Jonathan Osbourne

PhD., University of Maryland
Published author

Jonathan is a published author and recently completed a book on physics and applied mathematics.

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The electromagnetic spectrum depicts different frequencies of electromagnetic radiations shown from blue to red. On the electromagnetic spectrum, wavelength is shown to be increasing to the right and frequency is shown to be increasing to the left. The radiations in the order from blue to red on the electromagnetic spectrum are gamma, X-ray, UV, visible, IR, microwaves and radio waves with gamma being the smallest and radio waves being the biggest.

So let's talk about the electromagnetic spectrum, the big thing about the electromagnetic spectrum is trying to distinguish the differences between all the different wavelengths that are possible for electromagnetic waves, we can have lengths as small as 100 the size of an atomic nuclears and as big as the whole solar system or even bigger. And these are not going to behave the same way, so all these different characteristics give us the need to write down a spectrum like this. So we have wavelength increasing to the right frequency increasing to the left. Remember that we always have to have wavelength times frequency equals the speed of light which is a constant. Now we're going to be looking at this in terms of waves propagating in the vacuum now it's true light waves can also propagate through glass, through air, through water, through all kinds of things. Now when they do that their frequency will stay the same but their wavelengths will change.

Despite that fact it's customary to talk in terms of wavelength so we'll be doing that today but just remember that if you're looking at this in water the wavelengths are going to be different. Okay so the smallest wavelength electromagnetic waves are called Gamma rays, these gamma rays come as the result of nuclear reactions. They're rare but very, very dangerous. They'll come out of for example a hydrogen bomb that goes off there'll be gamma radiation that comes out and you don't want to be standing there. X-rays of course also come out of nuclear decays but they're not quite as dangerous. We use x-rays of course to take pictures of our bones. The reason why that works is that x-rays will penetrate through our skin but they'll be stopped by our bones so when we try to expose something the rays will all go through our skin they won't go through the bones and so that's what allows us to take a picture of the bones. Alright then we get into ultraviolet light ultraviolet light is what leads to sunburns when it comes from the sun thankfully most of that is stopped by the o-zone, that's because o-zone O3 will absorb these ultraviolet rays and turn into the more innocuous oxygen O2.

Alright then we get into visible light, visible light of course is associated with many different colors running the whole rainbow pretty much by definitions the smallest frequencies are the violets and the blues and then we run on through to the I'm sorry the smallest wavelengths so the blues the largest frequencies or the blues and then we run on into the largest wavelengths in the reds. So that's visible and of course we get that from the sun then we go into infrared. Infrared radiation is really something that you think about when you think about temperature thermo radiation. Where all our little light bulbs and the infrared basically because we've got temperature. Then we get into microwaves which are larger wavelengths and then we go up into the radio waves. Radio waves are useful because the atmosphere does not absorb them like it does microwaves and infrareds. Radio waves we can use to transmit information like radio signals, alright do let's look at this a little bit more specifically.