Question

1. Sound produced by an open pipe contains:

• Fundamental component only
• Odd harmonics only
• All the harmonics
• Even harmonics only

2. A pipe 30 cm long is open at both ends. Which harmonic mode of the pipe is resonantly exerted by a 1.1 kHz source?

3. Will resonance with the same source be observed if one end of the pipe is closed? (Take the speed of sound in air to be 330 ms^-1)

Answer 1

 1. All the harmonics.

2. We know frequency of oscillation in the Pipe, f = \(\frac{nV}{2L}\)

Substituting the values v, L and f we get

n = 2 means that the oscillation is second harmonics.

3. The condition for second harmonics in closed pipe is

The frequency required for resonance in a closed pipe is 825 Hz. Hence we do not get resonance at 1.1 Khz.