NTA Abhyas JEE Main2020PhysicsWaves and SoundPractice
An open pipe, when closed at one end, can resonate in its third harmonic with a frequency which is 100   Hz more than its fundamental frequency as an open pipe. If the fundamental frequency of the pipe when it is open at both ends is 50 n   Hz , then the value of n is
Correct answer
4
Step-by-step solution
Length of the organ pipe is same in both the cases. Fundamental frequency of open pipe is f 1 = v 2 l Frequency of third harmonic of closed pipe will be. f 2 = 3 v 4 l Given that, f 2 = f 1 + 1 0 0 or f 2 - f 1 = 1 0 0 or 3 4 v l - 1 2 v l = 1 0 0 ⇒ v 4 l = 1 0 0 ∴ v 2 l or f 1 = 2 0 0 Hz 50 . n Hz ⇒ n = 4 Therefore, fundamental frequency of the open pipe is 200 Hz. and n = 4