Waves Vocab Flashcards
longitudinal wave
displacement of particles in medium is parallel; to direction in which the wave transfers energy
transverse wave
displacement of particles in medium is perpendicular; to direction in which wave transfers energy
wave direction
direction of energy transfer for a wave
wave frequency
the number of waves that pass a point every second
wave speed
distance travelled per unit time; by a wavefront
amplitude
the maximum displacement of the medium from its equilibrium position
coherence
a constant phase difference between waves from different sources
monochromatic
an e-m wave of just one frequency/just one wavelength
ray
line indicating wave direction; perpendicular to wavefronts
wavefront
a line joining points on the wave that have the same phase / displacement; perpendicular to rays
plane polarised wave
a transverse wave; where the medium oscillates in just one plane N.B. only transverse waves can be polarised
Malus’s law
the intensity of light transmitted by a polarising filter is I = I0cos2θ
where:
I0 is the initial intensity of the incident light
I is the intensity of the transmitted light
θ is the angle between the axis of the filter and the direction of polarisation of the light
principle of superposition
where two or more waves meet; the resultant displacement at any point is found by adding the displacements produced by each individual wave
constructive interference
where waves meet and are in phase; larger amplitude oscillations result
destructive interference
where waves meet and are out of phase; smaller amplitude oscillations result
standing wave
a standing wave is formed when two waves travelling in opposite directions meet and interfere. They must be of the same frequency.
fundamental frequency
the lowest frequency of standing wave that can exist within a system (also called the 1st harmonic)
node
a point on a standing wave where the amplitude of the oscillation is zero
antinode
a point on a standing wave where the amplitude of the oscillation is at a maximum.
amplitude
the MAX distance a wave reaches form rest point
wavelength
the DISTANCE for 1 complete oscillation
period
the TIME for 1 complete oscillation
frequency
The nuber of oscillations in 1 second
Displacement
Distance travelled by a wave in a certain direction.
Phase difference
The fraction of a cycle between the oscillations of two particles, expressed in degrees.
Reflection
The bouncing back of a wave from a surface.
Refraction
The change in direction of a wave as it crosses an interface between two materials where it’s speed changes.
Diffraction
The spreading of a wave when it passes through a gap or past the edge of and object.
