M4- C11 Flashcards
progressive wave
a wave in which the peaks and troughs, or compressions and rarefactions, move through the medium as energy is transferred
longitudinal wave
a wave in which the medium is displaced in the same line as the direction of energy transfer- oscillations of the same medium particles are parallel to the direction of the wave travel
compression and rarefraction
sound waves
transverse wave
a wave in which the medium is displaced perpendicular to the direction of energy transfer- oscillations are normal to the direction of travel of the wave
peaks and troughs
eg. water, EM
displacement
distance from the equilibrium position in a particular direction; a vector, so has either +/- value
amplitude
maximum displacement from the equilibrium position (can be +/-)
wavelength
minimum distance between 2 points in phase on adjacent waves
e.g.one peak to another
period
the time taken for 1 oscillation
or time taken for wave to move one whole wavelength past a given point
frequency
the number of wavelengths passing a given point per unit time
wave speed
the distance travelled by he wave per unit time
phase difference
the difference between the displacements of particles along a wave
or the difference between the displacements of particles on different waves, measured i degrees or radians, with each complete cycle or a difference of one wavelength representing 360 or 2Pi radians
antiphase
if particles are oscillating completely out of step with each other (one reaches its maximum positive displacement at the same time as the other reaches its maximum negative displacement)
reflection
occurs when a wave changes direction at a boundary between 2 different media, remaining in the original medium
law of reflection
i=r
angle of incidence = angle of reflection
refraction
occurs when a wave changes direction as it changes speed when it passes from one medium to another
diffraction
when waves pass through a gap or travel around an obstacle, they spread out
polarisation
the phenomenon in which oscillations of a transverse wave are limited to only one plane
plane polarised
description of a transverse wave in which the oscillations are limited to only one plane
partially polarised
description of a transverse wave in which there are more oscillations in one particular plane, but the wave is not completely plane polarised- occurs when transverse waves reflect off a surface
intensity
radiant power passing through a surface per unit area
intensity and amplitude
intensity is directly proportional to amplitude^2
EM waves
transverse waves and can be plane polarised
radio waves
< x10^6
microwaves
x10^-1 to x10^-3
infrared
x10^-3 to 7x10^-7
visible light
7x10^-7 to 4x10^-7
ultra violet
4x10^-7 to x10^-8
xrays
x10^-8 to x10^-10
x ray and gamma ray
x10^-10 to x10^-13
gamma ray
x10^-13 to < x10^-16
total internal reflection
TIR
occurs at the boundary between 2 different media