howto:hambasics:temp
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howto:hambasics:temp [2019/11/25 17:24] – ve7hzf | howto:hambasics:temp [2019/11/25 18:25] – [Amplitude, Wavelength, Period, and Frequency] ve7hzf | ||
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- | * the // | + | * the // |
- | * the // | + | * the // |
+ | Now imagine that the animation is in super slow motion and that the waves are actually travelling at the speed of light, which is roughly 300,000,000 metres per second: How many times does each dot go up and down in one second? | ||
+ | Another way of asking that question is: how many full cycles can you fit in 300,000,000 metres (since radio waves travel 300,000,000 metres each second). | ||
+ | * Since the blue wave has a wavelength of 2m, it'll take 150,000,000 cycles to reach 300,000,000 metres. | ||
+ | * Similarly, since the green wave has a wavelength of 6m, its frequency is 50 Mhz. | ||
- | All EM waves (radio, light, etc) in vacuum travel at the speed, which is roughly | + | So a quick way to relate the frequency $f$ (in MHz) and the wavelength $\lambda$ (in metres): |
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+ | Note that the reason we're using just 300, instead of 300,000,000 is that we've cancelled 6 of the zeros so that the frequency is in MHz instead of in Hz. | ||
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+ | Now, here' | ||
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+ | * For the blue wave, we know that it oscillates 150,000,000 times / second, so only one of those time would take 150, | ||
+ | * Similarly, | ||
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+ | The time to complete one full cycle is called the //period (T)// and is the reciprocal of the frequency: | ||
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+ | ===== Old ===== | ||
Look at the following two waves. | Look at the following two waves. |