Topic 11: Wave Phenomena Flashcards
Principle of superposition
When two waves pass at a location, the resultant amplitude is the vector sum of the individual displacements.
Standing waves
Standing waves occur when two identical waves travelling in opposite directions superpose. The peaks move up and down but do not progress down the wave.
Node
A point on a standing wave which mains stationary due to destructive superposition.
Anti-node
A point on a standing wave which oscillates at maximum amplitude.
Standing wave and energy
They do not transport energy, but store it.
Standing wave and phase
All the points between adjacent antinodes are in the same phase. Adjacent nodes have a phase difference of π rad.
Standing wave in string
There is an antinode at the fixed end of a vibrating string. The reflected wave superposes on the incident wave.
Standing wave in pipes
A standing wave can arise in air in a pipe. At an open end there is a node; at a closed end, there is an antinode.
Fundamental mode
The lowest frequency mode of vibration of an oscillating system.
Harmonics
The different modes of vibration of an oscillating system.
Doppler effect
The change in frequency observed when a source of waves is moving relative to the observer.
Single slit diffraction
Waves passing through a narrow aperture is diffracted and interference effects cause a pattern of maxima and minima.
Double slit diffraction
Waves passing through two parallel slits interfere and produce maxima and minima. The separation of the fringes depends on the wavelength, slit separation and distance of the fringes from the slits.
Resolution
If two sources, close to each other, can be seen as separate, we say we can resolve them.
Rayleigh criterion
The minimum separation between two sources so that they can still be resolved by the observer. At the point that two sources can just be resolved, the central maximum of one source coincides with the first minimum of the other.
