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# Question from comprehension - sound watch

1. A note is played on a violin at the same time as a pure tone is emitted from a loudspeaker connected to a signal generator. When the generator frequency is set to 261 Hz, beats are detected. The beat frequency is 4 Hz.
--The phenomenon of beats is an example of the superposition of sound waves. Two pure tones of slightly different frequency played together produce a combined sound wave, the loudness of which rises and falls at a frequency called the beat frequency The beat frequency is the difference in freuency of the two pure tones. If the frequencies of the two pure tones are equal, they are in unison and only a single note is heard.--

Find two possible frequencies of the violin note, I got 257 Hz and 265 Hz (Dunno if it's right though)
Explain how, by altering the frequency of the signal generator once only, the actual frequency of the violin note could be determined.

Sorry bout the long post, its from a comprehension quetion and i didnt want to miss anything out. I'd really appreciate any help cos i am completely stuck with this
2. Yeah, you're right. "The beat frequency is the difference in frequency of the two pure tones", hence if the beat frequency is 4Hz, the violin must be either 4Hz above or 4Hz below the generator.

To determine the frequency of the violin, change the generator to either 257Hz or 265Hz. If when you change it, the beat pattern disappears, then you have found the frequency of the violin (it is that of the generator), because "If the frequencies of the two pure tones are equal, they are in unison and only a single note is heard". If the beat frequency increases, then you know its the other frequency.
3. Thank you mucho

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