can someone please explain to me the beat phenomena?

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I study physics I’m in the first year of university and I don’t understand why in the graph the cos part is like that when you draw the interference

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2 Answers

Anonymous 0 Comments

I feel like you are referring to a specific example from a textbook or something. I can’t help you with a specific graph if I can’t see it.

Unfortunately there isn’t much to explain here. Beat frequency are a result of the superposition of waves. Superposition is basically a fancy word for add. So if you add 2 waves with very similar frequencies (it doesn’t matter if it is sine or cosine), you will get a beat frequency.

I think what you are confused about is that **the beat frequency is the frequency of change in amplitude** of the superimposed waves, not the frequency of the wave itself

Check out this link to actually hear what I am talking about: [https://ophysics.com/waves10.html](https://ophysics.com/waves10.html)

The tone you hear is the frequency of the wave. The “wah-wah-wah-wah” is the beat frequency and it is the changing of the amplitude of the wave.

Anonymous 0 Comments

So think of when you’re sitting at a stop light and you and the person in front of you have your blinker on. Most of the time, the blinkers blink at two slightly different rates. Maybe you turn them on at the same time so in the beginning the blinks happen at almost the same time (your blinker and their blinker turn on and off at the same time). After some time passes, due to the different blink rates, the blinks now get out of sync and now when your blinker turns off theirs turns on. Wait a little bit longer and now their synced up again.

Now instead of on/off think of the peaks and troughs of sine waves. If they have slightly different wavelengths/frequencies, at one point, the peaks and troughs will line up almost exactly, just like the blinkers lined up. This gives you constructive interference and the waves add together. However, at another point, the peaks line up with the troughs (like when your blinker is on when theirs is off). When you add these parts together, they cancel out and give destructive interference.