Y1 Ch 05 Definitions Flashcards
Progessive wave.
A wave that travells through a substance or space, transferring energy.
Amplitude
The maximum displacement from the undisturbed position.
Wavelength
The distance between peaks.
Frquency
The number of cyclea per second
Period
The time for one complete cycle.
Phase difference
The fraction of a wave cycle between two points along a wave.
Longitudinal waves
Particles vibrate parallel to the direction that energy travels in.
Transverse waves
Vibrations are at right angles to the direction that energy travels in.
Electromagnetic waves
Transverse waves all of which travel at the speed 3*10^8 m/s
Mechanical waves
Cannot travel throgh a vacuum, but need a medium to travel through.
Polarised wave
When the oscillations of the wave are confined to one plane.
Refraction
The change in direction at a boundary when a wave travels from one medium to another.
Angle of incidence
The angle between the refracted ray and the normal
Angle of refraction
The angle between the refracted ray and the normal.
Refractive index
The ratio of a wave’s speed between two materials
Total Internal Reflection
The complete reflection of light at a boundary within a material that has a higher refractive index than its surroundings.
Critical angle
The angle of refraction for which the angle of incidence is 90 degrees
Optic Fibre
A thin glass (or plastic) fibre that transmits light
Step index optic fibre
An optic fibre with a uniform refractive index in the core and a smaller uniform refractive index for the cladding
Material dispersion
The spreading of a signal caused by the variation of refractive index with wavelength
Pulse broadening
When the duration of a pulse increases as a result of dispersion in an optic fibre
Modal dispersion
The spreading of a signal caused by rays taking slightly different paths in the fibre
Absorption
When energy from a signal is absorbed by the optical fibre
