Q138 / 180 · COMEDK 2017 · Physics

The disc of a siren containing 60 holes rotates at a constant speed of $360 \mathrm{rpm}$. The emitted sound is in unison with a tuning-fork of frequency

  • A
    $10 \mathrm{~Hz}$
  • Correct answer
    B
    $360 \mathrm{~Hz}$
  • C
    $216 \mathrm{kHz}$
  • D
    $6 \mathrm{~Hz}$

Solution

The number of waves produced by the disc is equal to number of notes i.e., $\quad n=60$ Speed of rotation, $v=360 \mathrm{rpm}$ $=\frac{360}{60}=6 \mathrm{rps}$ $\therefore$ Frequency $=n \times v=60 \times 6=360 \mathrm{~Hz}$

Hence, the correct answer is option: 'B'.

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