Waves

Different types of waves

Transverse- Propagation (direction of movement) perpendicular to oscillation eg a sine curve.
Longitudinal- propagation parallel to direction of oscillation
Mechanical- Require a medium to travel through
Electromagnetic- Do not require a medium to travel through- can travel through a vacuum
Plane waves- are straight
Circular waves- in circles, spread out
Pulse- A short section of wave, no repeated up and down motion
Continuous wave- a model used by physicists to ensure they are modelling the middle of a plane wave. Do not exist in reality.
Wave trains- have a beginning and an end

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Wavelength = distance between two "equal" points on a wave eg crest to crest
Frequency = number of waves per second
Time period = time taken for one wavelength to pass a point
Velocity = velocity of the wave
V=fw
f=1/T and T=1/f
V=w/T
Amplitude = greatest distance from the equilibrium position (maximum displacement)

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Points on a wave that are a whole wavelength apart are in phase
Points half a wavelength apart are in antiphase
Principle of Superposition: when more than one wave meets in one place, the total displacement from the equilibrium position is the sum of the displacements of all the waves
Must take into account the direction of displacement
Applies to all waves

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Are caused when a wave is reflected back from a hard object or, for example, a string is tied at two points- superposition leads to the formation of a "stationary wave"
The amplitude must be 0 at both ends for string tied at both ends, so w=2l/n
l=length of string
n=an integer... 1,2,3... etc
w=wavelength

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