-
A cylindrical resonance tube open at both ends, has a fundamental frequency, ƒ, in air. If half of the length is dipped vertically in water, the fundamental frequency of the air column will be
-
- 2ƒ
- 3ƒ/2
- ƒ
- ƒ/2
Correct Option: C
Fundamental frequency of open pipe,
| ƒ = | ||
| 2l |
When half of tube is filled with water, then the length of air column becomes half
| l' = |  |  | |||
| 2 |
and the pipe becomes closed.
So, new fundamental frequency
| ƒ' = | = | = | |||||||
| 4l' | 4 | | | 2l | |||||
| 2 | |||||||||
Clearly ƒ' = ƒ.
