12.6 Flashcards
What are the conditions for a stationary wave to be formed in a tube with one open end
• Antinode at open end
-oscillation of air is at greatest amplitude therefore antinode
• Node at closed end
-air cannot move therefore node
What features do the fundamental mode of vibration in a one open ended tube have
- Node at closed end
- Antinode at open end
- Only one of each
What variables dictate the value of the fundamental frequency of stationary waves in pipes with one open end
- Density (of air)
- Temperature (of air)
• These dictate speed of wave
-therefore dictate value of fundamental frequency
What are the harmonics of a stationary wave in a one closed ended tube
- First harmonic = 1xf0
- 1/4λ
- Third harmonic = 3xf0
- 3/4λ
- Fifth harmonic = 5xf0
- 5/4λ
• Only odd harmonics of fundamental frequency can form
What are the conditions for a stationary wave to be formed in a tube with both open ends
• Antinodes at both ends
-oscillation of air is at greatest amplitude therefore antinode
What variables dictate the value of the fundamental frequency of stationary waves in pipes with both open ends
- Density (of air)
- Temperature (of air)
• These dictate speed of wave
-therefore dictate value of fundamental frequency
What are the harmonics of a stationary wave in a both open ended tube
- First harmonic = 1xf0
- 1/2λ
- Second harmonic = 2xf0
- 2/2 (1) λ
- Third harmonic = 3xf0
- 3/2λ
• Each harmonic of fundamental frequency can form
How is speed of sound investigated in a resonance tube
- 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
