14.2 Standing Waves: Open + Closed Tubes

Standing wave in a bottle: Where do we find the node + antinode when blowing across the top of a pop bottle?

• Node at the bottom, antinode at the top

• Node at the top, antinode at the bottom

• Node at the middle, antinode at both ends

• Node at both ends, antinode in the middle

Briefly describe the anatomy of a closed pipe system: Standing waves in a closed end system. Which of the following describes the wavelengths within the fundamental?

• There is 1/4 of a wavelength with 1 Node + 1 Antinode

• There is 3/4 of a wavelength with 2 Nodes + 2 Antinodes

• There is 5/4 of a wavelength with 3 Nodes + 3 Antinodes

Briefly describe the anatomy of a closed pipe system: Standing waves in a closed end system.

Which of the following describes the wavelengths within the 5th harmonic?

• There is 1/4 of a wavelength with 1 Node + 1 Antinode

• There is 3/4 of a wavelength with 2 Nodes + 2 Antinodes

• There is 5/4 of a wavelength with 3 Nodes + 3 Antinodes

What is the fundamental frequency for an empty pop bottle that has a Length of 0.20 m (20 cm)?

*Assume wave speed is 343 m/s.

f₁ = (v / 4L)

• 274 Hz

• 343 Hz

• 429 Hz

• 588 Hz

The fundamental frequency for an empty pop bottle that has a Length of 0.20 m (20 cm) is 429 Hz.

What is the 3rd harmonic frequency?

*Assume wave speed is 343 m/s.

f₁ = (v / 4L)

• 822 Hz

• 1,029 Hz

• 1,287 Hz

• 1,764 Hz

The fundamental frequency for an empty pop bottle that has a Length of 0.20 m (20 cm) is 429 Hz.

What is the 5th harmonic frequency?

*Assume wave speed is 343 m/s.

f₁ = (v / 4L)

• 2,145 Hz

• 2,029 Hz

• 1,987 Hz

• 1,764 Hz

The fundamental wavelength of a particular bottle is 0.64 m. What is the length of the bottle?

f₁ = (v / 4L)

• 0.16 m

• 0.32 m

• 0.48 m

• 0.64 m

A bottle is to be used as a musical instrument. Suppose we would like the fundamental frequency of the bottle to be 400.0 Hz.

If the bottle is 24.0 cm tall, how much water should it be filled with water to produce the desired frequency?

f₁ = (v / 4L) and (H = h + L)

• Add about 3.0 cm

• Add about 4.0 cm

• Add about 5.0 cm

• Add about 6.0 cm

Open Pipe: Find the 5th Harmonic in the picture. There are ____ Nodes and ____ Antinodes.

• 1; 3

• 2, 3

• 3; 4

• 4, 5

Open Pipe: The frequency of the standing wave in the open pipe shown below is 360 Hz. How long is the pipe?

f = v / 2L *Assume speed = 343 m/s

• 35 cm

• 48 cm

• 52 cm

• 58 cm