Standing Waves
Standing waves (also known as stationary waves) occur when waves are reflected, or in pipes or air columns, when two oppositely travelling waves interfere.
Certain points are called nodes, a point of no amplitude (represented
as r).
At other points are anti-nodes, a point of maximum amplitude (represented
as a).
How to create a standing wave using microwaves
Reflect the waves from a transmitter causing the waves to interfere to produce a standing waves. It is then possible to calculate the frequency by measuring the distance between nodes, which corresponds to half a wavelength and then using v = f? with v = 3x108 ms-1
Half a wavelength is also known as the 1st Harmonic.
Fundamental vibration which can be formed by plucking the middle of a string with both ends fixed.
Pipes and Air Columns
For a standing wave in a closed pipe the nodes are at the ends and anti-nodes are at the open ends.
Progressive and standing waves
Similarities:
Particles vibrate longitudinally and have the same frequency and amplitude
Differences:
Progressive waves particles have amplitude
Progressive waves transfer energy
Standing waves have node particles which don't move
Standing waves have no phase differences between particles