12.6 Stationary waves in air columns Flashcards
How do sound waves that are reflected off a surface form stationary waves?
The original wave and the reflected wave travel in opposite directions and superpose. Hence creating a resultant wave with displacement as the sum of the individual displacements of the original and reflected waves.
Another way that stationary sound waves can be made?
- Making the air inside a tube vibrate at frequencies related to the length of the tube. The stationary wave formed depends on whether the ends of the tune are open or closed.
- The air at the closed end cannot move, and so must form a node. At the open end, the oscillations of the air are at their greatest amplitude, so it must be an antinode.
- When air is blown into a tube (like a flute or clarinet), sound waves travel through the air and reflect at the tube’s ends. The reflection causes interference between the incoming and reflected waves, forming a stationary wave with nodes (N) and antinodes (A).
How do you form stationary waves in open tubes?
A tube open at both ends must have an antinode at each end in order to form a stationary wave.
What does the term ‘resonance’ mean?
Resonance is when something vibrates strongly and naturally at a particular frequency — and it happens when a system is exposed to vibrations or waves that match its natural frequency.
What is the fundamental harmonic?
The fundamental harmonic is the lowest frequency at which a system can naturally vibrate
Describe a simple method for the formation of stationary sound wave using a speaker, a microphone, and a solid surface, and how to use it to determine the wavelength of sound produced from a signal generator.
- Connect speaker to a signal generator
- Position the speaker in front of the solid surface with the microphone in between.
- Adjust the speaker by observing the oscilloscope connected to the microphone so that a number of nodes and antinodes are detected.
- Measure the distance between two nodes and multiply that by two to get the wavelength.
