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Turning fork A of frequency 305 Hz produces 5 beats `s^(-1)` with another turing fork B. After filling tuning fork B, it produces 3 beats `s^(-1)` with A. The frequency of B before filling wasA. 300 HzB. 313 HzC. 310 HzD. 308 Hz |
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Answer» Correct Answer - A The phenomenon of beats is used in the determination of unknown frequencies. Suppose `v_(2)` is the unknown frequency of a tuning fork B. Let this fork B produce m beats per second with another tuning fork A of known frequency `v_(1)`, As number of beats/s is equal to difference in frequency of two sources. Therefore, `v_(2) = v_(1) +- m` When the prong of fork B is filed a little, it becomes lighter and its frequency of vibration increases on sounding the filed fork B with fork A, we count the number of beats `s^(-1)`. Proceeding as, we conclude that, if number of beats `s^(-1)` on filing fork B of unknown frequency increases, m would So, frequency of tuning fork B `= 305 +- 5 = 310 Hz, 300Hz` Since, on filing tuning fork B, number of beats decreases. This means that frequency of B should be less ie, 300 Hz |
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