# A pipe in air at 20°C is to be designed to produce successive harmonics at 225 Hz, 275 Hz, and 325 Hz. Is the pipe open or closed? How long does the pipe need to be?

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Which harmonics are these?

Which harmonics are these?

##### 1 Answer

Apr 30, 2018

Given,

Three harmonics, all **odd** multiples of

For open pipes,

For half-open pipes (e.g. closed),

The key to this question is knowing that "closed" pipes must have harmonics in odd multiples, to ensure an antinode being at the open end and a node being at the closed end.

Hence, the pipe is **closed** , the fundamental frequency is