P3 - Waves Flashcards
What is amplitude?
Max displacement from equillibrium position.
Where is the antinode?
At the position of maximum displacement of a stationary wave.
What quality should cladding have?
Lower refractive index.
When are waves coherent?
When they have the same wavelength and frequency, and a fixed phase difference.
What is diffraction?
Spreading of waves as they pass through a gap of similar magnitude to their wavelength.
What is interference?
Superposition of waves.
What is material dispersion?
Waves of different wavelengths travelling at slightly different speeds and broadening the pulse.
How to overcome material dispersion?
Use monochromatic light.
What is modal dispersion?
Waves entering the fibre at slightly different angles so distance that each beam travels is different, broadening the pulse.
Where is the node?
Position of minimum displacement in a stationary wave.
What is path difference?
A measure of how far ahead a wave is compared to another wave, usually expressed in terms of wavelength.
What is polarisation?
Restricting the oscillations of a wave to a single plane.
What is the refractive index?
The ratio between C and the speed in the given material.
What is a stationary wave?
A wave that stores but doesn’t transfer energy.
When does total internal refraction occur?
When the light is moving into a material of lower refractive index, and hits the boundary at an angle greater than critical.
