2What is a wave?A repeating disturbance or movement that transfers energy through matter or spaceWaves transfer energy not matter.Waves can only exist as they have energy to carry.The water waves to theright are carrying energy butare not moving.
3What are mechanical waves? They require a medium.A medium is a form of matter (a substance or material) through which the wave travels and it can be a solid, liquid or gas.They are not capable of transmitting its energy through a vacuum (empty space), such as light from the sun
4What are mechanical waves? They are produced when a source of energy causes a medium to vibrate.Vibration is a repeated back and forth or up and down motionThere are two types of mechanical waves based on how the wave moves:Transverse WavesLongitudinal Waves
5Transverse WavesThe matter vibrates perpendicular (at right angles) to the direction of the waveElectromagnetic waves and light wavesAnimation courtesy of Dr. Dan Russell, Kettering University
6Transverse Wave Properties The crest is the highest pointThe trough is the lowest pointThe rest position is the horizontal line representing the rope (medium) before it was disturbed.The wavelength is the distance from one point on the wave to the next corresponding adjacent point, such as crest to crest or trough to tough
7Longitudinal WaveThe matter vibrates parallel (same) to the direction of the wavesound wavesAnimation courtesy of Dr. Dan Russell, Kettering University
8Longitudinal Wave Properties The area squeezed together is called compressions like the crests on a transverse waveIn the picture, where the parts of the medium (coils of the Slinky) are closer together than normalThe areas spread out are called rarefactions like the troughs on a transverse waveIn the picture, where the parts of the medium are farther apart than normal
9Sound WavesSound is a longitudinal wave which travels through the air through a series of compressions and rarefactions.Sound travels through air, but travels through other materials as well.
12What is sonar?Sonar is a system that uses the reflection of underwater sound waves to detect objects. This has been used to find sunken ships and schools of fish.
13What are seismic waves?An energy wave which vibrates through the earth’s crust as the crust bends or breaks.Seismic waves exist as transverse (secondary waves), longitudinal (primary waves) and both types (surface) of waves.Some travel through the earth (P and S waves) and some travel across the earth’s surface (surface waves).
14Animation courtesy of Dr. Dan Russell, Kettering University
15Surface Waves A combination of longitudinal & transverse Animation courtesy of Dr. Dan Russell, Kettering University
16AmplitudeThe amplitude of a wave is directly related to the energy of a wave.The amplitude of a longitudinal wave is determined by the closeness of the compressions. The closer the compressions and the farther the rarefaction lines.The amplitude of a transverse wave is determined by the height of the crest or depth of the trough.
17Wavelength and Frequency Wavelength is the distance between two corresponding parts of a wave.Transverse wave: a measure of distance from crest to crest or trough to troughLongitudinal wave: a measure of the distance between one compression and rarefaction to the nextFrequency is the number of waves that pass through a point in a certain amount of time.The unit for frequency is waves per second or Hertz (Hz).One Hz = One wave per second.
18Wavelength and Frequency Wavelength and frequency are inversely related.A decrease in the wavelength, means the more times the wave will pass through a point in one second (an increased frequency).The larger the wavelength (or increased wavelength), the fewer times it will pass through a point in one second (a decreased frequency).
19Electromagnetic Waves Wave which is capable of transmitting its energy through a vacuum (i.e., empty space)Produced by the vibration of electrons within atoms on the Sun's surfaceTravel through space until they reach Earth