Frequency & Wavelength Relationship

hey guys what's happening today we are going to talk about frequency and wavelength pardon my arm I'll get it out of there in a second there you go frequency and wavelength and before we start to really get into it let's just go through really quick the parts of the wave so that we're you know what I'm talking about okay so this is a a representation of a sine wave like you'd see on an oscilloscope the Y AIS represents the amplitude or the magnitude or the overall strength of the wave the x axis represents time so if we say here this is you know 0er seconds and over here this is I don't know3 seconds well this wave has happened how many times in3 seconds and that's one of the things we're going to talk about so the first thing we need to know when we say wavelength what do we mean by wavelength let's talk about the parts of the wave the parts above the zero line up here towards the top this part of the wave right here this is called the crest and it's opposite down here is called a trough and one wavelength is from the top of one Crest or one trough to the other and it is represented as the Greek letter Lambda all right are you with me so now we know the parts of the wave and we can talk about frequency and wavelength because they're all very interconnected all right so frequency and my definitions are my definitions they're not the Webster's definitions I take them from the Webster's definition and I'm just trying to make it easier for folks who don't have a lot of experience to understand what we're talking about so frequency is the number of times that a complete waveform and that is Crest to Crest is repeated in a fixed time and that was our time there remember from 0 seconds to3 seconds so what is a wavelength then that's the other side of the question right well wav length is basically it's reciprocal it is the distance between two adjacent Peaks whether they be crests or troughs and it is inversely proportional to the wavelength now there's one more thing we need to add into this so we can do just a couple of equations nothing nothing too serious we're not going to get any differential calculus but we need to know C and C of course is the speed of light why do we need to know the speed of light well because electrons travel at the speed of light and they travel through wires and conductors at a somewhat diminished rate but still very close to the speed of light and our speed of light and I am going to I want to I want to I want to make this easy for you to do the math kind of round this up let's do that let's just call it 300 million m per second all right so those are our three components we need to talk about with frequency and wavelength we talked about wavelength is uh shown as Lambda frequency is just displayed in well it's displayed in hertz they can be megahertz kilohertz Hertz um gigahertz but they are Hertz and HTS herts of course is uh repetitions per second wavelength is expressed as a matter of length so we could have millimeters meters kilometers you know we can go all the way we can have nanometers picometers now we've got everything we need to be able to do just a little calculation and the calculation is pretty simple and it just says that Lambda you remember Lambda right that's a wavelength Lambda is equal to C the speed of light divided by F the frequency and really that's all the math that we're going to get into here today so if you know your frequency you just take the speed of light divided by the frequency and you get Lambda which is your wavelength why is all this important well it's just different ways to be able to identify and characterize this electromagnetic force in in different manners and this is especially true when you want to talk about groups of frequencies you know for instance say you're operating on a VHF frequency of 145 megahertz well that's one specific frequency so yes you can say I'm operating on 145 megahertz and that's very specific but if you don't need to be that specific you can say I'm operating on 2 MERS 2 MERS is the wavelength so we use it we use this a lot in amateur radio in professional radio as well anytime you're dealing with waves like this so I'm going to show you the the um amateur radio ones CU they're the ones that I am familiar with all right and I'm not going to draw you a horrible chart I'm simply going to whip out this little thing from the ARRL the American radio relay league so remember I told you wavelengths can be any length at all so here is 2200 M wow that's a long wave that is the distance from one one Crest to the second crest and that covers the frequencies of 135 khz to 137.84 M and if you don't speak metric 630 m is about 2,000 ft or 167 yards so that is an American football field and a half for that wave to start reach its CEST reach its trough and then reach the next C well I'm sorry I miss I misspoke from the time it reaches its Crest to its trough to its next crest that is super long then we go up to 160 m which equates to about 1.8 mahz that's um a very low band a lot of amateurs use this one is really good for long distance late night Communications then we have 80 M which is around 3.5 to you know 4 MHz 60 M and it just keeps going up and up and up and up and up to 6 M there's 2 MERS that we talked about 25 70 CM this is uh this is UHF 70 CM that's you know that's not very long at all then we can get up here into the microwave and all these other frequencies so it's just easier instead of saying that you're going to be working on something between 14.1 75 MHz and 14.35 MHz to say you're working in the 20 M BAND people will will understand what you mean you know it's it's pretty simple that way all right now we're not going to get too far into the leads but you know just to close this out a a few Advanced points in the case of traveling waves which means radiated energy radio waves I mean you know it could be anything the frequency of wave of the wave is correlated to the wavelength of the wave and the speed at which the wave is traveling so if the wave is Mo moving faster the number of complete Cycles in 1 second is more than when it's moving slower so it's very important in determining his frequency and an important note decide this is two different waves can have different wavelengths on the same frequency so if you assume that Wave 1 has a wavelength of 1 cmet and wave two has a wavelength of 2 cm well they can have the same frequency but one will be traveling twice as fast as the other yeah I hope that that makes a little bit of sense to you guys the relationship between frequency and wavelength so I mean why is it important I me if you're going to be messing around electrical engineering that's just things that you need to talk about but in a practical sense it becomes important especially when designing antennas you know for instance an antenna to work on the 40 meter band The 7 mahz band from let's say 7 megahertz to 7.3 megahertz is going to have to be in the area of 66 feet long for a halfwave antenna 66 ft that's a big antenna however at the other end of the spectrum uh the UHF that we just talked about I'm unscrewing an antenna over here if you wonder what I'm doing the UHF Spectrum here is a UHF dipole cut for 435 mahz it is a little over uh 40 m 40 yeah I forget see one second 33 cm long so half the wavelength sorry it's too early for math it's only4 to two in the afternoon all right guys that's about all I got to say about that for today I hope you enjoyed this video if you did please give me a thumbs up feel feel free to comment share and don't forget to subscribe big thanks to all the patrons guys the patrons are the only thing that are keeping this channel going right now um if you're not a patron please consider joining this uh this is April 2024 and this is uh the first month since I've had this channel in 2018 I haven't been able to pay my utilities out of the revenue of this channel so I'm not going to be able to keep this up much longer if it continues this way all right that's all I got peace

Channel: learnelectronics

Views: 1,377

Keywords: frequency, wavelength, learnelectronics, physics, chemistry, amplitude, waves, speed of light, Amazon shop, electronic components, Greek letter λ

Id: XFLYvKawcSI

Length: 12min 9sec (729 seconds)

Published: Thu Apr 18 2024