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14. waves and sound — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics14. waves and sound1 Mark
MCQ
$41$ forks are so arranged that each produces $5$ beats per sec when sounded with its near fork. If the frequency of last fork is double the frequency of first fork, then the frequencies of the first and last fork are respectively
  • ✓
    $200, 400$
  • B
    $205, 410$
  • C
    $195, 390$
  • D
    $100, 200$
✓

Answer

Correct option: A.
$200, 400$
a
(a) $n_{First} = n_{First} + (N -1)x$ 

$2n = n + (41 -1) × 5$

$\Rightarrow$ $n_{First} = 200 Hz$ and $n_{Last} = 400 Hz$

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