NTA Abhyas JEE Main2020PhysicsWaves and SoundPractice
A closed pipe of length 22 c m , when excited by a 1875 H z source forms standing waves. The number of pressure nodes formed in the pipe are [velocity of sound in air = 330 m s - 1 ]
Options
- A1
- B2
- C4
- D3
Correct answer
D. 3
Step-by-step solution
Velocity of sound = 330   m   s - 1 Length of closed pipe = 22   cm = 22 × 10 - 2  m The fundamental frequency of the stationary wave, ν 0 = v 4 l = 330 4 × 22 × 10 - 2 = 330 × 10 2 4 × 22 = 3000 8 ν 0 = 375   Hz 3 ν 0 = 375 × 3 = 1125   Hz 5 ν 0 = 5 × 375 = 1875   Hz 5 th harmonic Number of nodes = 3 Note: In a closed pipe, odd harmonics are produced.