4.4 - Waves Flashcards
What is a progressive wave
A wave which transfers energy from one point to another with a wave front that travels through the material
What is a longitudinal wave
A wave which oscillates in the same direction as the energy (rarefactions and compressions)
What is a transverse wave
A wave where the particles oscillate perpendicular to the energy (like EMF waves)
What is frequency measured in
Hertz (Hz)
What is wavelength
The distance between 2 adjacent points (e.g. peaks)
How to find time period of a wave using frequency
T = 1 / f
What is phase difference
The amount one wave lags behind another as proportion of the wavelength (measured in radians or degrees)
What do the axis on an oscilloscope measure
Vertical = Voltage / Amplitude
Horizontal = Time
What is refraction
It is when a wave bends at a boundary between 2 materials due to the change in density causing it to speed up or slow down
What is the difference between a polarised and unpolarised wave
Polarised waves contains waves oscillating along one axis. Unpolarised waves can be oscillating in any direction perpendicular to the axis of propagation
How is intensity defined in terms of power
Intensity is power / area
How fast do Electromagnetic waves travel in a vacuum
3x10^8 ms^-1 (speed of light)
What is refractive index
The refractive index is a measure of how fast light travels in a material compared to its speed in a vacuum
How to find refractive index of a material
n = c / v
n = refractive index
c = speed of light
v = velocity when in the material
What is the name of the angle of incidence at which the light will reflect off a boundary rather than refracting in the medium
The critical angle
How do you find the critical angle
SinC = 1 / n
C = critical angle
n = refractive index of material being passed into