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InterviewSolution
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What are the beats? Define beat frequency. Explain how the frequency of a tuning fork is determined using beats. |
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Answer» The periodic rise and fall (Waxing and waning) in the intensity of sound due to the superposition of two sound waves of slightly different frequencies traveling in the same direction is called beats. The number of beats heard per second is called the beat frequency and is equal to the difference in the frequency is of the two sound waves. To determine the unknown frequency of a tuning fork Step 1: Consider a tuning fork A of known frequency f and another fork B of unknown frequency f'. When A and B are sounded together let m beats are heard/sec, ∴ f' = f ± m Step 2: Let one of the prong of B is loaded with a bit of wax. The two forks are again sounded together and let m be the number of beats heard/sec. f m’ > m, i.e. betas increases after adding wax, then real frequency of B is = f – m If nr’ < m, i.e. betas decreases or remains same after adding wax, then real frequency of B is f' = f + m. |
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