12.6

Question 1

What are the conditions for a stationary wave to be formed in a tube with one open end

Answer 1

• Antinode at open end
-oscillation of air is at greatest amplitude therefore antinode

• Node at closed end
-air cannot move therefore node

Question 2

What features do the fundamental mode of vibration in a one open ended tube have

Answer 2

• Node at closed end
• Antinode at open end
• Only one of each

Question 3

What variables dictate the value of the fundamental frequency of stationary waves in pipes with one open end

Answer 3

• Density (of air)
• Temperature (of air)

• These dictate speed of wave
-therefore dictate value of fundamental frequency

Question 4

What are the harmonics of a stationary wave in a one closed ended tube

Answer 4

• First harmonic = 1xf0
• 1/4λ
• Third harmonic = 3xf0
• 3/4λ
• Fifth harmonic = 5xf0
• 5/4λ

• Only odd harmonics of fundamental frequency can form

Question 5

What are the conditions for a stationary wave to be formed in a tube with both open ends

Answer 5

• Antinodes at both ends

-oscillation of air is at greatest amplitude therefore antinode

Question 6

What variables dictate the value of the fundamental frequency of stationary waves in pipes with both open ends

Answer 6

• Density (of air)
• Temperature (of air)

• These dictate speed of wave
-therefore dictate value of fundamental frequency

Question 7

What are the harmonics of a stationary wave in a both open ended tube

Answer 7

• First harmonic = 1xf0
• 1/2λ
• Second harmonic = 2xf0
• 2/2 (1) λ
• Third harmonic = 3xf0
• 3/2λ

• Each harmonic of fundamental frequency can form

Question 8

How is speed of sound investigated in a resonance tube

Answer 8

• Hold tuning fork above open end of close ended tube
• Air vibrates at same frequency as tuning fork
• Length of tube can be changed by moving tube further into water until tuning fork frequency matches f0
• Length of tube must be 1/4λ
• Speed of sound is v = fλ (λ = 4L) (f = tuning fork frequency)
• L corresponding to fundamental mode of vibration is recorded for different tuning forks when investigating speed of sound