Waves Definitions Flashcards
(20 cards)
Progressive Wave
Distributes energy from source point to surrounding area, by moving energy in form of vibrating particles.
Displacement
Distance from equilibrium position in particular direction in metres.
Amplitude
Maximum displacement, metres
Wavelength
Minimum distance between 2 points in phase on adjacent waves.
Frequency
No wavelengths passing a given point per unit time, hertz
Time period
Time for 1 complete oscillation to pass, seconds
Transverse Wave
Oscillations are perpendicular to direction of energy transfer
Longitudinal Wave
Oscillations are parallel to direction of energy transfer.
Phase Difference vs Path Difference
Difference between the displacement particles along a wave (in degrees or radians) vs fractions of a wavelength
Reflection
Wave changes direction at boundary between 2 diff media, remain for in original medium.
Refraction
Wave changes speed when passing across the boundary between 2 diff media and change direction
Increase speed, bend towards normal
Wavelength changes not frequency
Refractive Index
Ratio of velocity of light in a vacuum to take velocity in a specified medium.
Total Internal Reflection
Occurs at boundary between 2 diff media and all light is reflected back to original medium.
Diffraction
Waves pass through gap or travel around obstacle and spread out.
Polarisation / plane polarised
Particles oscillate along 1 direction only
Transverse wave
Electromagnetic Waves
Transverse waves, electric and magnetic fields oscillating at right angle to each other.
Principle of superposition
When 2 or more waves cross the resultant displacement equals the vector sum of the individual displacements
Coherent waves
Same wavelength and frequency and fixed phase difference between them
Constructive vs Destructive interference
Crest to crest, trough to trough
(1 wavelength or 360 or 2pi)
vs
crest to trough
(1/2 wavelength or 180 or pi)
Line spectrum
Light emitted from excited isolated atoms produce a line spectrum
