JCECE Medical JCECE Medical Solved Paper-2015

  • question_answer
    Two tuning forks P and Q sounded together and 6 beats per second are heard. P is in unison with a 30 cm air column open at both ends and Q is in resonance when length of air column is increased by 2 cm. The frequencies of forks P and Q are

    A)  90 Hz and 84 Hz

    B)  100 Hz and 106 Hz

    C)  96 Hz and 90 Hz

    D)  206 Hz and 200 Hz

    Correct Answer: C

    Solution :

     We know that \[f=\frac{v}{2l}\] Fundamental frequency of an open organ pipe). Number of beats heard = 6 \[\Rightarrow \] \[{{f}_{P}}-{{f}_{Q}}=6\] or \[\frac{v}{2(0.3)}\frac{v}{2(0.32)}=6\] or \[v=\frac{2\times 0.3\times 0.32\times 6}{0.32-0.3}\] Now, \[{{f}_{P}}=\frac{v}{2(0.3)}=\frac{0.32\times 6}{0.02}=96\,Hz\] and \[{{f}_{Q}}=\frac{v}{2(0.32)}=\frac{0.3\times 6}{0.02}=90\,Hz\]


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