Waves

Terms	Definitions
Period	The time it takes for one complete vibration/oscillation/cycle. Units are in seconds. The inverse of frequency
Frequency	The number of cycles/vibrations/oscillations per second. Units are the Hertz (Hz) which stands for cycles/sec. The inverse of period.
Simple Harmonic Motion	Motion that repeats.
Crest	The highest point of a wave.
Trough	The lowest point of a wave
Amplitude	The distance from equilibrium point to the highest or lowest point of a wave. In mechanical waves it is proportional to the energy of the wave.
Wavelength	The distance from crest to crest or trough to trough or any point on a wave to the next point where it repeats the motion.
Equilibrium point	The resting position of an oscillator where it would eventually come to rest.
Wave speed	Dependent on properties of the medium such as density and temperature.
Transverse wave	A wave whose medium oscillates at right angles to the direction of the waves' energy.
Wave	A vibration in space and time.
Longitudinal wave	A wave whose medium oscillates parallel to the direction of the waves' energy.
Compression	A region of high pressure of the medium in a longitudinal wave.
Rarefaction	A region of low pressure of the medium in a longitudinal wave.
Electromagnetic waves	Travel at the speed of light. Do not require a medium. The denser the medium, the slower it travels.
Mechanical waves	Require a medium. The denser the medium the faster they travel.
Interference	The interaction between 2 or more waves.
Constructive interference	When two waves interact and result in an increased amplitude.
Destructive interference	When two waves interact and result in decreased amplitude.
Reflection	When a wave bounces of a boundary and travels in a new direction.
Refraction	The bending of a wave due to a change in the medium's properties.
Diffraction	The bending of a wave around an obstacle or through a hole.
Absorption	When a wave encounters a boundary and as a result, loses some or all of its energy.
Standing wave	A stationary wave pattern formed in a medium when two sets of identical waves pass through the medium in opposite directions.
Reverberation	A reflection of a sound wave
Doppler effect	change in the apparent frequency of a wave as observer and source move toward or away from each other
Radio waves	longest wavelength and lowest frequency light wave.
medium	The matter that transmits the energy of the wave. Does not travel with the wave's energy.
Infrared waves	Sensed as heat.
Visible light wave	What humans are able to detect with eyes.
Ultraviolet waves	Has enough energy to ionize DNA
X-Rays	Are absorbed by bones.
Gamma rays	Electromagnetic waves with the shortest wavelengths and highest frequencies. Stars naturally emit these.
node	the place in a standing wave where there is no displacement
anti-node	the place in a standing wave where there is maximum displacement
pitch	corresponds to frequency in sound