390
8 Waves
Resonance with tuning forks of different frequencies is possible because
resonance for f = 210 occurs with the first overtone of the tube and for
f = 350 it occurs with the second overtone.
8.86 f =
v
2L
(open pipe, fundamental)
f 1 =
v
L
(open pipe, first overtone)
f 2 =
5v
4L
(closed pipe, second overtone)
f 2 − f 1 = 100 (by problem)
5v
4L
−
v
L
=
v
4L
= 100
∴ Fundamental frequency of open pipe, f =
v
2L
= 200 Hz.