NEETPhysicsWaves and Sound
An open organ pipe has a fundamental frequency f . It is dipped vertically into water such that a certain fraction of its length is submerged. Match the submerged fraction in List-I with the ratio of the new fundamental frequency to the original fundamental frequency ( f'/f ) in List-II. List-I (Submerged fraction) List-II ( f'/f ) (A) 1/2 (I) 1 (B) 3/4 (II) 2 (C) 1/3 (III) 3/4 (D) 1/4 (IV) 2/3 Choose the correct ans
Options
- A(A) (I), (B) (II), (C) (III), (D) (IV)
- B(A) (II), (B) (I), (C) (IV), (D) (III)
- C(A) (I), (B) (III), (C) (II), (D) (IV)
- D(A) (II), (B) (IV), (C) (I), (D) (III)
Correct answer
A. (A) (I), (B) (II), (C) (III), (D) (IV)
Step-by-step solution
Let the original length of the open pipe be L . Its fundamental frequency is f = v 2L . When a fraction x of the pipe is submerged, the length of the air column remaining is L' = L(1 - x) . The pipe now acts as a closed organ pipe. Its new fundamental frequency is f' = v 4L' = v 4L(1 - x) . The ratio of the new frequency to the original frequency is: f' f = v 4L(1 - x) v 2L = 1 2(1 - x) For (A) x = 1/2 : f' f = 1 2(1 - 1/2) = 1 For (B) x = 3/4 : f' f = 1 2(1 - 3/4) = 2 For (C) x = 1/3 : f' f = 1 2(1 - 1/3) = 3 4 Fo