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32. Electromagnetic Waves

The Electromagnetic Spectrum


The Electromagnetic Spectrum

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Hey, guys, in this video, we're gonna talk about something called the electromagnetic Spectrum. Okay, let's get to now. Light of different energy acts dramatically different. Okay, high energy light acts totally different than low energy light. And there are particular what we would call regions off energy or light acts pretty much the same. So we arranged something called the electromagnetic spectrum, which is just an arrangement of light based on its energy into groupings of equal or sorry groupings off similar energy that share similar properties. Okay, the energy of light is proportional to the frequency of the light, and so it's inversely proportional to the wavelength of the light. Okay, so in this diagram right here, if I step to the side, you can see frequency here. Frequency is increasing to the left, so energy is increasing to the left wavelength is doing the opposite. We've length up at the top is increasing to the right, and you can actually see that light over here is very short. Wavelength and light over here is very long wavelength. Okay, so this graph is set up for you to read it as energy and frequency increasing to the left wavelength increasing to the right and the most important thing to keep track of is the energy that the light contains. Okay, so there are several different spectra within this several different regions, Several different regimes, whatever the word might be. We have radio waves. We have microwaves. We have infrared visible and ultraviolet which are very, very, very tightly packed. Then we have X ray, and we have gamma ray. Okay, so let's look at the properties of those different types of light. Okay, Now, radio waves are the longest wavelength and lowest energy electromagnetic waves. They're used to transmit information over long distances. That's why your radio is called the radio because it receives and transmits radio waves. Okay, Microwaves happened toe have just the right amount of energy toe vibrate water molecules in food, which is why microwave ovens are very good at hitting up things. And they heat things up pretty quickly because the rate at which the energy is absorbed by the food is much faster than that in a traditional oven. But all the microwave oven is doing is it's blasting the food with microwave radiation, which is pretty low energy light, and that's causing the water to vibrate inside of the food, which through friction and through other things, is releasing the heat and it heats up the food. Okay, Now, visible light, which I've paired really with infrared and ultraviolet is the portion of the spectrum that you can see. You technically can't see infrared light, and you technically cannot see ultraviolet light. But they're very, very, very closely sandwiched on either end of the visible light spectrum. If you look above me back at the figure in the visible light, they've actually colored in it. Okay, The acronym that typically refer Sorry, the acronym that typically used for the visible light spectrum to remember how the colors are arranged in terms of lowest energy, the highest energy. So remember, on this graph on this figure, that's to the left low energy. The high energy is typically refer to his Roy G. Biv. You read it like Roy Jean give okay. And it stands for red, orange, yellow, green, blue, indigo and violet. Okay, um, some textbooks have dropped the indigo. Some professors might drop the indigo, but indigo does go right there in between blue and violet. It doesn't really matter Either way, the most important thing to remember is that red is the lowest energy light. Okay, red and infrared is the lowest energy. And blue or violet, technically, and ultraviolet is the highest energy. Okay, white light is not a true color. It doesn't belong in the visible spectrum. What white light is is it's a combination of multiple colors that, for some reason, trip our photo cells in our eyes into appearing white. Okay, It doesn't have to be all the colors of fluorescent light bulbs. For instance, use four or five different colors. Um, but it has to be a combination of multiple colors across the spectrum to create white light. Okay, next our X rays, which are the lowest energy type of ionizing radiation. Okay, ionizing radiation is the kind of radiation that does really damage toe living organisms and all that it means by ionizing is if you have a little Adam. So we have a nucleus with the proton. We have an electron all happy in its shell. This ionizing radiation comes in. So this x ray and it kicks the electron out. It ionized is the atoms, so it removes an electron. Okay, having all of those electrons hanging around outside of atoms is extremely damaging toe living organisms. It damages DNA bonds when those DNA bonds that are damaged are then repaired. Oftentimes, mistakes are made during those reparations during the repair mint. Sorry, and those mistakes lead to things like cancer. Okay, low energy X rays are very useful, however, in medical imaging, as long as you don't get hit by them over and over and over and over there. Most commonly used in X ray machines, as the name implies, and C T or CAT scans, which stands for computed tomography or computer animated tomography. Those scans are basically like rotating X ray machines that take, ah few 100 to 1000 X rays off you from different angles and conform using a computer. Ah, three dimensional model of what's going on inside of you. One other medical instrument that I didn't mention that uses X rays is something called the fluoroscope, which is like a video X ray. So it takes X rays 20 times a 2nd 10 times a second or something, so you can see a moving image like a video of what's going on through you Okay, So those air instances where X rays were very useful But those air once again low energy X rays because high energy, X rays air very, very, very damaging. All right. And the last bit I couldn't quite fit in that frame was gamma rates. Okay. Gamma rays are the highest energy form of electromagnetic radiation. They are another type of ionizing radiation, and they are extremely hazardous toe living organisms. Okay, there are very, very few, um, practical uses for gamma rays and medicine. For instance, there's a type of cancer therapy called gamma knife therapy that uses very targeted gamma rays to kill tumor cells. But besides that, they're typically found or sorry. They're typically shielded from ever reaching humans by massive layers of lead. You do not want gamma rays to touch you, okay, Gamma rays or the cause of most damage from nuclear weapons or nuclear plant meltdowns. Both nuclear weapons and nuclear plants, um, involves splitting atoms and the amount of energy that's released when atoms air split is so high that it produces gamma rays. And those gamma rays go off in all sorts of different directions and they're very, very damaging. Very very bad for you. Okay? And there's all sorts of other side effects that I'm not gonna get into from something like a nuclear plant meltdown. Like at Chernobyl. Okay, let's do a quick example and then get out of here. Which is more energetic long wave radio waves or shortwave radio waves. Okay, remember, energy is proportional to frequency, so it's inversely proportional to wavelength. So the longer the wavelength, the less energy it has. The shorter the wavelength, the mawr energy it has. So which is more energetic? Short wave radio waves those air Definitely more energetic Because energy is proportional to one over the wavelength. It's inversely proportional to the wavelength. Alright, guys. So that wraps up our discussion on the electromagnetic spectrum. Thanks for watching.