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MHT CET202619 April 2026Morning ShiftPhysicsWaves and SoundActual

A tuning fork gives 5 beats per second with a 33 cm length of sonometer wire. If the length of the wire is shortened by 1 cm, the number of beats is still the same. The frequency of the fork is

Options

  1. A320 Hz
  2. B325 Hz
  3. C330 Hz
  4. D340 Hz

Correct answer

B. 325 Hz

Step-by-step solution

Let the frequency of the tuning fork be n . The frequency of a sonometer wire is inversely proportional to its length, f 1 L . Let f₁ and f₂ be the frequencies of the wire for lengths L₁ = 33 cm and L₂ = 32 cm respectively. Since L₂ f₁ . The tuning fork gives 5 beats per second with both lengths. Thus, f₁ must be less than n and f₂ must be greater than n . n - f₁ = 5 f₁ = n - 5 f₂ - n = 5 f₂ = n + 5 Using the relation f₁ L₁ = f₂ L₂ : (n - 5) 33 = (n + 5) 32 33n - 165 = 32n + 160 n = 325 Hz Answer: 325 Hz

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