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

Gujarat BoardEnglish MediumSTD 11 SciencePhysics14. waves and sound1 Mark
MCQ
When two tuning forks (fork $1$ and fork $2$ ) are sounded together, $4$ beats per second are heard. Now some tape is attached on the prong of the fork $2$. When the tuning forks are sounded again, $6$ beats per second are heard. If the frequency of fork $1$ is $200 \,Hz$, then the original frequency of fork $2$ is ........... $Hz$
  • A
    $204$
  • ✓
    $196$
  • C
    $202$
  • D
    $200$
✓

Answer

Correct option: B.
$196$
b
(b)

Frequency of fork $1=200 \,Hz$

Frequency of fork $2=200 \pm 4$

When tape is added frequency of fork $2$ decreases.

When frequency of fork $2$ decreases number of beats increases.

Hence we know frequency of fork $2$ is

$f_2=200-4=196 \,Hz$

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