Waves Flashcards
Amplitude (A) (wave)
maximum displacement of the medium from the equilibrium position
Amplitude (Xo) (SHM)
maximum displacement from the equilibrium position
Analyser
a device that can detect polarised light
Antinode
position of maximum displacement
Brewster’s law
when light reflects off a surface it will be 100% polarised in
the plane of the surface if the angle between the reflected and refracted rays is 90
Coherent
wave sources that have a fixed-phase relationship
Compression
part of a longitudinal wave where the particles are closest together
Constructive interference
occurs when waves meet in phase to give max displacement
Critical angle (θc)
angle of incidence above which total internal reflection may occur
destructive interference
occurs when waves meet out of phase to give zero displacement
diffraction
spreading out of waves past an obstacle or through a gap
Displacement (x) (SHM)
instantaneous distance from the equilibrium position in a specific direction
Displacement (x)(wave)
instantaneous distance the medium has moved from the
equilibrium position in a specific direction
Electromagnetic waves
do not require a medium so can travel through a vacuum
Frequency (f) (SHM)
number of oscillations per se
Frequency (f)(wave)
number of oscillations of the medium per sec
fundamental frequency (fo)
the lowest frequency standing wave that can be formed in a pipe or on a string
intensity (I)
power per unit area received by an observer
isochronous oscillation
an oscillation with a constant time period
longitudinal wave
the particles of the medium oscillate parallel to the direction of energy transfer
Malus’ law
I = Io cos^2 θ
Mechanical waves
require a medium through which to travel
Node
position of zero displacement
optically active substance
substance that rotates the place of polarised light as the light passes through it
path difference
difference in distance travelled by two different waves, given in terms of wavelength
Period (T)(SHM)
Time for one oscillation
Period (T)(wave)
time for one complete oscillation of the medium (or for a complete wave to pass a given point)
Polarised light
light in which the electric field vector is oscillation on one plane only
Rarefaction
part of a longitudinal wave where the particle are furthest apart
Ray
shows the direction of energy transfer of a wave
refraction
the change in speed of a wave that occurs when it travels into a different medium
refractive index (n)
a measure of how fast a wave travels in a medium
restoring force (SHM)
a force that is always directed towards the equilibrium position
simple harmonic motion
an oscillation where the force (and acceleration) is proportional to
displacement from the equilibrium position but is in the opposite direction
Snell’s law
n = sin i/sin 4
Standing wave
a wave formed when a wave is reflected and the reflected wave interferes with the forward moving wave
Superposition
a resultant wave formed by the addition of the displacements of individual waves when they interfere
Total internal reflection
occurs when a wave is travelling into a less dense medium and when the angle of incidence at the boundary is greater than the critical angle
Transverse wave
the particles of the medium oscillate perpendicular to the direction of energy transfer
wave
a movement of energy through a medium
wave speed (c)
distance travelled per unit time by the energy of the wave
wavefront
line connecting points along a wave that are in phase
wavelength (λ)
shortest distance along a wave between two points that are in phase
