12 - Waves 2 Flashcards
What is the principle of superposition?
When two waves meet at a point, the resultant displacement at that point is equal to the sum of the displacements of the individual waves.
What is superposition?
When waves overlap and produce a wave with a different displacement.
What is interference?
When two progressive waves continuously pass through each other and superpose, producing a resultant wave.
What is constructive interference?
When two waves that are in phase superpose, the resultant displacement will be greater than the displacement of each wave.
What happens to intensity when you increase amplitude?
It increases
Intensity =k(amplitude^2
What is destructive interference?
When two waves that are in antiphase superpose, the resultant displacement is lower than the displacement of each wave.
What happens when two waves with the same amplitude meet in antiphase?
The resultant wave has an amplitude of 0.
If two sound waves superposed in phase, what would happen to the sound?
It would get louder.
What is an interference pattern?
When two waves spread out and superpose at different points, producing a pattern of minima and maxima.
What is required for a stable interference pattern?
The waves must be coherent.
What is coherence?
The two waves must have a constant phase difference.
The same frequency and wavelength.
What is a maxima?
Constructive interference.
What is a minima?
Destructive interference.
What is path difference?
The difference in the distance that two waves have traveled from their sources.
What is path difference measured in?
Metres
Often in n(wavelengths) — wavelength is measured in metres
Describe the path difference that will cause two waves to meet at a point in phase.
A whole number of wavelengths.
0,1,2,3…
Describe the path difference that will cause two waves to meet at a point in antiphase.
A half number of wavelengths.
1/2 3/2 5/2 7/2 …
Describe the point where two waves would meet if their path difference was 100 wavelengths.
Maxima
Describe the point that two waves would meet at if their path difference was 50.5 wavelengths.
Minima
What is the central maxima?
A maxima where the path difference is 0.