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Question: Answered & Verified by Expert
A string 2.0 m long and fixed at its ends is driven by a 240 Hz vibrator. The string vibrates in its third harmonic mode. The speed of the wave and its fundamental frequency is
PhysicsWaves and SoundJEE MainJEE Main 2019 (09 Apr Shift 2)
Options:
  • A 320  m s-1,  120 Hz
  • B 320  m s-1,  80 Hz
  • C 180  m s-1,  80 Hz
  • D 180  m s-1,  120 Hz
Solution:
2623 Upvotes Verified Answer
The correct answer is: 320  m s-1,  80 Hz
For a string fixed at both the ends,
f=n2Lv
For third harmonic, 240=32(2)v
v=240×43
=320  m s-1
Fundamental frequency f0=12Lv
=14×320=80Hz

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