CHARACTERISTICS of Waves Mrs. Clarici Wave a disturbance that transfers energy from place to place caused by energy Vibration a repeated back and forth or up and down motion Medium material through which a wave travels mechanical waves require a medium to travel through (ex. sound) electromagnetic waves do not need a medium to travel through (ex. light)

Mechanical Waves Mrs. Clarici Mechanical waves are produced when a source of energy causes a medium to vibrate Types: Classified by how they move 1. Transverse waves 2. Longitudinal (compression) waves 1. Transverse Waves “trans” means across

Mechanical Waves Mrs. Clarici 2. Longitudinal (Compression) Waves

Transverse vs. Longitudinal mrs. clarici

wave properties mrs. Clarici Amplitude - maximum distance that the particles of the medium carrying the wave move away from their rest position. The more energy there is the greater the amplitude or compression. Wavelength - the distance between two corresponding parts of a wave. Frequency - the number of complete waves that pass through a given point in a certain amount of time. - measured in units called hertz (Hz) 1 Hz = 1 wave/second Speed -how far a wave travels in a given length of time speed = wavelength x frequency

interactions of waves mrs. clarici Reflection - when an object or wave hits a surface through which it cannot pass, it bounces back. Law of Reflection angle of incidence = angle of reflection Normal - drawn perpendicular to the surface at the point where the wave hits the surface

interactions of waves mrs. clarici Refraction When a wave enters a new medium at an angle, one side of the wave changes speed before the other, causing the wave to bend.

interactions of waves mrs. clarici Diffraction When a wave moves around a barrier or through an opening in a barrier, it bends and spreads out.

interactions of waves mrs. clarici Interference - interaction between waves that meet Constructive interference When waves combine to make a bigger wave (greater amplitude). Destructive interference When waves combine to make a smaller wave (less amplitude). Dark lines show sound cancelation.

interactions of waves mrs. clarici Standing Waves - an incoming wave and a reflected wave have just the right frequency so the combined wave appears to be standing still. Resonance - an increase in amplitude of a vibration that occurs when external vibrations match an object’s natural frequency.

Seismic waves mrs. clarici Waves Produced by Earthquakes “seismos” means earthquake (Greek) Primary (P) Waves longitudinal waves move fastest Secondary (S) Waves transverse waves cannot pass through liquids Surface Waves combination of transverse and longitudinal move slowest move along surface of a medium tsunamis - huge surface waves Seismograph records ground movements caused by seismic waves as they move through Earth.