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JCECE Medical JCECE Medical Solved Paper-2002

  • question_answer
    A tuning fork gives 4 beats with 50 cm length of a sonometer wire. If the length of the wire is shortened by I cm the number of beats is still the same. The frequency of the fork is:

    A)  396 Hz       

    B)  400 Hz

    C)  404 Hz       

    D)  384 Hz

    Correct Answer: A

    Solution :

     According to law of length of a stretched string \[n\propto \frac{1}{l}\] or,       \[{{n}_{1}}{{l}_{1}}={{n}_{2}}{{l}_{2}}\] Given,\[{{n}_{1}}=n-4,{{n}_{2}}=n+4,{{l}_{1}}=50\,cm,\] \[{{l}_{2}}=49\,cm\] Hence, \[(n-4)\times 50=(n+4)\times 49\] or \[50n-200=49n+196\] or \[n=396\,Hz\]


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