Chapter 3- Waves: Stationary Waves Flashcards
What is a stationary wave?
The superposition of 2 progressive waves with the same frequency and amplitude.
The waves are moving in opposite directions.
No energy is transmitted.
Define the term resonant frequencies.
The frequency that causes the progressive waves to produce an exact number of waves. (When they are both on the same string).
What is a node?
Points on the stationary wave where the amplitude is 0.
What is an antinode?
Points of maximum displacement on a stationary wave.
What is the first harmonic?
The lowest possible resonant frequency a stationary wave vibrates to.
Only one half wavelength fits on the string.
Wavelength = 2 x length of string
What is the second harmonic?
It has twice the frequency as the second harmonic.
2 half wavelengths fit on the string.
Wavelength = length of string.
What is the third harmonic?
3 x the frequency of the first harmonic.
1.5 wavelengths fit on the string.
Wavelength = 2/3 length of the string.
How can you show stationary microwaves?
Reflect a microwave beam at a metal plate.
The superposition of the wave and its reflection produces a stationary wave.
A probe can be moved to find the nodes and antinodes.
How can you show stationary sound waves?
Connect the loudspeaker to a tube of air with powder in.
The powder in the is shaken away from the antinodes but left undisturbed at the nodes.
