# Waves - Definitions

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**Mechanical waves: ** “propagate as oscillations of matter”
The velocity of a particle along a wave is not the same as the velocity of the wave.
**Pulse:** Single wave bump
**Continuous or Periodic wave: **The source is a vibration or oscillation
**Crests**: High point
**Troughs:** Low point
**Amplitude (From Oscillations):** Maximum height of a crest or depth of a trough.
**Wavelength [math] lambda [/math] (Lambda):** Distance between two crests (one after other)
**Frequency f:** Number of complete cycles (Number of crests) per second
**Period T**: 1/f, time between crests passing by same point
**Wave velocity v:** The velocity at which wave crests move forward. [math] v = lambda f v= lambda \ T [/math]
**Transverse wave:** vibration up and down (rope)
**Longitudinal wave**: vibration along the direction of the waves motion (Slinky)
**Compressions:** Areas where longitudinal wave is close together
**Expansions:** (Also known as **rarefactions**) Area’s where longitudinal waves are far apart.
**Intensity: **Average power transferred across area perpendicular to the direction of energy flow