WAVES 6.P.1.1 Compare the properties of waves to the wavelike property of energy in earthquakes, light and sound.

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. are rhythmic disturbances that carry energy without carrying matter.

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 3 typestypes: Longitudinal,transverse,surface

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 Surface Waves: Vibration is circular Ex.) Ocean waves; surface waves

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 90º or perpendicular to the direction of the motion of the wave

Characteristics of a Transverse Wave  Wavelength - the distance between one wave crest and the next (or between one wave trough and the next).  Frequency - the number of complete waves or cycles that pass a fixed point in a specific unit of time.  Amplitude - the size of the displacement or change caused by the wave.  Speed - a measurement of how fast a wave passes through a medium.  Crest - the point on a transverse wave with the greatest positive displacement from equilibrium.  Trough - the point on a transverse wave with the greatest negative displacement from equilibrium.

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

Waves 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!)

Electromagnetic Waves Electromagnetic waves can transfer energy through both a medium and empty space. Light is an electromagnetic wave. Light waves from the sun are able to travel through empty outer space to our planet. There are other types of electromagnetic waves besides visible light. These waves are invisible, but they can travel through a vacuum, such as outer space, and carry energy from place to place. They do not need matter to move, but they can pass through some types of matter like light through a window. Visible light, radio and TV waves, and X-rays are some examples of electromagnetic waves.

CHARACTERISTICS OF ELECTROMAGNETIC (EM) WAVES Waves are described according to their  Amplitude measures DISPLACEMENT size of the disturbance  Wavelength distance of a “repeating unit” Also called a cycle  Velocity v speed = how fast wave travels Electromagnetic waves are transverse waves. Their characteristics are the same as transverse waves.

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

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

Frequency ƒ  measured in wavelengths/second or cycles/second Hertz (Hz) = number of wavelengths in 1 second  Frequency is related to velocity: v = ƒ  Frequency is related to velocity: v = ƒ  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 Period = 1 Frequency

 Which of the following is true about sound waves and light waves? A. Most sound waves are longitudinal waves, while light waves are transverse waves. B. All sound waves and light waves are transverse waves. C. All sound waves and light waves are longitudinal waves. D. Most sound waves are transverse waves, while light waves are longitudinal waves.

 Which letter corresponds to the crest of the wave? A. Z B. W C. X D. Y

 Energy from an earthquake travels A. At the same speed through solids, liquids, and gases. B. Fastest through the gases of Earth’s atmosphere C. As light waves that warm the rock underground. D. As seismic waves that cause matter to vibrate.

 Waves transport _________ over distances. A. liquids B. solids C. gases D. energy

THE END!!! Catching some Waves