Chapter 13. Beat frequency (13-25)

Question

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Question

B3C8CigSgzNwYNiym2y9XXp0QUNVCNh32iZDuq5TjlguRA7CIjfR+fp2LuQEn6k1
{"title":"Beat frequency heard when sound waves of two similar frequencies interfere","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"rect\",\"coords\":\"1,7,23,59\"}]"} {"title":"Frequencies of the individual sound waves","description":"Correct!","type":"correct","color":"#993300","code":"[{\"shape\":\"rect\",\"coords\":\"159,8,186,56\"},{\"shape\":\"rect\",\"coords\":\"240,7,270,59\"}]"}

Review

To see how beats arise, let’s see what happens when we combine two sinusoidal waves with the same amplitude A but with slightly different frequencies \(f_1\) and \(f_2\). Figure 13-21 shows the result: The total wave is also a sinusoidal wave whose frequency \(f\) is the average of \(f_1\) and \(f_2\), but with an amplitude that varies between 0 and \(2A\). We use the term beats for this up-and-down variation in amplitude. The frequency of the beats, also called the \(\textbf{beat frequency}\), is equal to the \(\textit{absolute value}\) of the difference between the two frequencies: