WAVES DEFINITIONS Flashcards
Amplitude
The maximum displacement of a particle from its equilibrium position.
Antinode
A position of maximum displacement in a stationary wave
Cladding
A protective layer on an optical fibre that improves the tensile strength, prevents scratching and signal transfer between adjacent fibres
Coherence
Waves are coherent if they emit waves with a constant phase difference, and they have the same wavelength and frequency
Diffraction grating
A plate with many closely ruled parallel slits
Diffraction
The spreading of waves as they pass through a gap or near an edge that is similar to their wavelength
Electromagnetic Wave
A wavepacket of photon consisting of transverse electric and magnetic waves in phase and at right angles to eachother
Frequency
The number of complete wave cycles that pass a point per second
Interference
The formation of points of cancellation or reinforcement where two coherent waves pass through eachother
Laser
A light source that produces a parallel and coherent beam of monochromatic light
Longitudinal Wave
A wave with oscillations that are parallel to the direction of wave propagation
Material Dispersion
Waves of different wavelengths travel at different speeds through an optical fibre
And so reach the end of the fibre at different times
Causing pulse broadening
Modal Dispersion
Waves enter an optical fibre at slightly different angles, meaning the distance each beam has to travel is different
The beams reach the end at different times
Causing pulse broadening
Node
A fixed point of minimum displacement in a stationary wave
Optical Fibre
A thin transparent glass fibre through which signals are passed
Path difference
the difference in distances from two coherent sources to an interference fringe
Phase Difference
The difference in phase between two points on a wave
Polarisation
The restriction of a wave so that it can only oscillate in a single plane
Pulse Broadening
The elongation of a signal passed down an optical fibre
Stationary Wave
A wave that stores energy
Transverse Wave
A wave with oscillations that are perpendicular to the direction of wave propagation
Total Internal Reflection
A light ray travelling in a substance is totally internally reflected at a boundary with a substance of a lower refractive index, if the angle of incidence is greater than the critical angle
Wavelength
The distance between two identical positions on two adjacent waves
Young’s Double Slit Experiment
Demonstrated the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes.
Principle of Superposition
When two waves cross, the resultant displacement equals the vector sum of the individual displacements.
