WAVES

WAVES  Carries energy from one place to another  Classified by what they move through 1. Mechanical Waves the energy is transferred by vibrations of medium (medium = matter) ex/ ocean waves move through water 2. Electromagnetic waves (EM Waves) the energy moves through disturbances in the electromagnetic field. a disturbance that transfers energy

WAVE STRUCTURE CREST (peak) AMPLITUDE resting to max peak WAVELENGTH TROUGH

MECHANICAL WAVES travel through & gradually lose energy to that medium  Examples: water, sound, rope, & spring waves water, sound, rope, & spring waves  Mechanical Media: water, air, rope, spring water, air, rope, spring require a medium ( the material through which the disturbance is moving) to transmit energy Making a pulse

MECHANICAL WAVES Classified by how medium vibrates Pulse = direction of energy transfer Vibration = direction of vibration of medium relative to pulse 2 typestypes: Longitudinal& Transverse

MECHANICAL WAVES Classified by how medium vibrates Longitudinal Waves: Vibration is in the same direction as wave pulse (parallel to wave pulse) Transverse Waves: Vibration is at 90 0 (right angles) to wave pulse

TRANVERSE WAVES  Sideways or up & down  Examples: S-type earthquake waves S-type earthquake waves Electromagnetic (EM) or light waves Electromagnetic (EM) or light waves Vibration is perpendicular to the direction of the motion of the wave

LONGITUDINAL WAVES  Back and forth (compression & rarefraction)  Also called compression or pressure wave  Examples: P-type earthquake waves P-type earthquake waves Sound waves Sound waves Vibration is parallel to the direction of the motion of the wave Rarefraction (expansion) Compression

CHARACTERISTICS OF WAVES Waves are described according to their  Amplitude measures DISPLACEMENT size of the disturbance  Wavelength distance of a “repeating unit” Also called a cycle  Frequency ƒ Number of waves that

AMPLITUDE Distance between “rest & crest” or “rest & trough” Distance between “rest & crest” or “rest & trough” Gives indication of “power” or “strength” of wave (magnitude of earthquake = Richter scale) Gives indication of “power” or “strength” of wave (magnitude of earthquake = Richter scale) Does not affect velocity of wave Does not affect velocity of wave Determines loudness (sound) or brightness (EM wave) Determines loudness (sound) or brightness (EM wave)

WAVELENGTH WAVELENGTH  Distance between any two repeating points on a wave crest-crest, trough-trough, expansion-expansion, compression-compression  Determines what colors we see; what notes we hear (pitch)  Shorter wavelengths have more cycles per minute because they aren’t as long

Frequency ƒ  measured in wavelengths/second or cycles/second Hertz (Hz) = number of wavelengths in 1 second  How often number of wavelengths that pass any point per second

PERIOD T  How long Amount of time for one wavelength to pass a point  Related inversely to frequency T = 1 f Period = 1 Frequency

VELOCITY v  the rate at which the energy travels; speed & direction  Depends on medium Mechanical waves travel faster through dense mediums Mechanical waves travel faster through dense mediums EM Waves are faster through less dense mediums EM Waves are faster through less dense mediums The Velocity Formula V= x ƒ

Waves that describe the Earth S waves move through solids only!!! P waves move through solids & liquids Are these MECHANICAL WAVES???? YES!! Seismic waves need a medium (the earth!)