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Table of Contents
Amplitude, Wavelength, Period, and Frequency
This is an old revision of the document!
Picture of travelling 2m wave
Imagine that the dots moving up and down are creating the waves that are travelling to the right (as we'll see later, this is kind of like how radio waves are created). Here are a few things to notice:
To quantify observations more precisely, let's look at a snapshot of both waves.
Snapshot of the waves
All EM waves (radio, light, etc) in vacuum travel at the speed, which is roughly 300,000 metres per second. Now, let's take a snapshot of the two waves
Look at the following two waves. How are they different?
At first sight:
These two observations can be quantified very precisely as:
So the previous two waves have:
The amplitude is normally related to the strength of the signal (like the volume for sound).
Since the period (T) is the amount of time it takes to complete one cycle, and the frequency (f) is the number of cycles in one second, the period and the frequency are inverses of each other:
<latex> \qquad $$f = \frac{1}{T} \qquad \Leftrightarrow \qquad T = \frac{1}{f}$$</latex>
<box 80% blue> In this course, we'll see a few formulas and it'll be tempting to memorize them but let's instead understand what they really mean... </box>
For example:
Right?
So for the previous two waves, the frequencies would be:
Recall that Hz means “cycle per seconds”. That's why when we divide a number of cycles by time, we get Hertz.
Let's now look at three different ways to encode a signal on a radio wave.
: add $f=\frac{c}{\lambda}$