Answer :
The frequency of the first possible harmonic after the fundamental frequency in the open-closed pipe 428.75 Hz.
Calculation:-
A. L = 80 cm
= 0.8 m
V = 343 m/s ( sound speed in the air )
V1 = n V / 2 L
= 1 X 343 / 2 X 0.8
V1 = 214.375 Hz
B. using the above equation
Vf = V / 2 L
[tex]Vf\alpha 1 / L[/tex]
so the new frequency is high than the previous or before.
C. Now L = L / 2 = 0.8 / 2
L = 0.4 m
Vn = n V / 2 L
= 1 X 343 / 2 X 0.4
Vn = 428.75 Hz
so the new frequency is 428.75 Hz
D. Vn = n V / 2 L
L = L /2
Vn = 2 n V / 2 L
Vn = 2 n Vn
n = 2n
Vn = n' Vn
even multiples of the fundamental frequency
E. for open-closed pipe
fn = n V / 4 L
and for an open- open pipe
Vn = n V / 2 L
n V / 2 L = n V / 2 L
2 L = L
L = L / 2
So half the length of open-open Pipe.
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