WAVES

amplitude

a waves maximum displacement from its equilibrium position

displacement

the distance and direction that a vibrating particle or wave has travelled from its equilibrium position 

frequency

the number of complete oscillations of a wave cycle per second.

intensity

the power transferred per unit area.

longitudinal wave

a wave with oscillations that are parallel to the direction of energy travel. e.g. sound waves

period 

the time it takes for one complete wave to pass a given point. 

phase difference

the difference in phase between points on a wave, expressed in radians

polarisation

the restriction of a wave so it can only oscillate in a single plane. only occurs in transverse waves. 

progressive waves

a wave that transfers energy from one point to another, without the transfer of matter

transverse waves

a wave with oscillations that are perpendicular to the direction of energy transfer. e.g. electromagnetic waves 

wavelength

the distance between two identical positions on two adjacent waves.

wave speed

the product of a waves frequency and wavelength

antinodes 

a position of maximum displacement in a stationary wave 

coherence

waves with the same frequency and constant phase difference

constructive interference

interference that occurs when two waves meet in phase. the wave amplitudes are superposed

destructive interference

interference that occurs when two waves are in anti phase. one wave is at a peak and the other is at a trough, their addition results in a minimum point.

diffraction

the spreading out of a wave as it passes through a gap, or around an obstacle

diffraction grating

a grating with hundreds of slits per millimetre that results in sharper interference patterns when a wave passes through it. 

interference

the superposition of the amplitudes of waves when they meet

nodes

a position of minimum displacement in a stationary wave

superposition

when two waves meet at the same point in space their displacements combine and the total displacement at that point becomes the sum of the individual displacements at that point