Verified Solution • 2025–26 Session moderate

QJEEM21Phd988: JEE Main 2021 Physics - Class 11 JEEM21Phd988 Solution: A tuning fork A of unknown frequency produces 5 beats/s with a…

A tuning fork A of unknown frequency produces 5 beats/s with a fork of known frequency 340 Hz. When fork A is filed, the beat frequency decreases to 2 beats/s. What is the frequency of fork A?

Multiple Choice Options

  • A 335 Hz
  • B 345 Hz
  • C 338 Hz
  • D 342 Hz

Step-by-Step Verified Solution

Initially beat frequency = 5Hz

so, ρA = 340 ± 5 = 345 Hz, or 335 Hz

after filing frequency increases slightly so, new value of frequency of A > ρA

Now, beat frequency = 2Hz

⇒ new ρA = 340 ± 2 = 342 Hz, or 338 Hz

hence, original frequency of A is ρA = 335 Hz

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