Waves Part II Behavior Standing Waves Standing waves

Waves Part II: Behavior

Standing Waves • Standing waves are a result of interference. • • • – Combination of incident and reflected waves Two waves of equal amplitude and wavelength pass in opposite directions. Node – stationary point where waves are always out of phase. Antinode – largest point of amplitude The Wave Machine http: //www. cbu. edu/~jvarrian/applets/waves 2/simwav_g. htm

Standing Waves Due to interference Nodes “out of Phase” Antinodes “In phase”

Interference - waves combine Destructive or Constructive Interference http: //users. erols. com/renau/wave_interference. html

Principle of Superposition • When two or more waves meet, there is • • • interference. The displacement caused by two or more waves is the algebraic sum of the individual waves Constructive interference – waves in phase add Destructive interference – waves out of phase subtract

Reflection • When wave reaches a • barrier at least part of the wave bounces back. Angle of incidence equals the angle of reflection • http: //www. physicsclassroom. com/mm edia/waves/fix. html

Change in Media • A place where the substance the wave is traveling • • through changes Example: A light wave traveling through air passes through a glass window Some of wave is transmitted and some is reflected

Refraction • When a wave travels • • in a different medium the velocity changes This change in velocity results in bending of the wave. This is why a pencil appears to bend in a glass of water.

Diffraction • Waves normally travel • • in a straight line in a medium. When waves meet a barrier, they bend around the edges. This is called diffraction. • http: //www. control. co. kr/java 1/mason g/oneslit. html

The Doppler Effect • The apparent change • in frequency of a wave due to the motion of the source or receiver. Greater speeds produce greater effects. http: //library. thinkquest. org/19537/java/Doppler. html http: //www. control. co. kr/java 1/masong/doppler. html

Doppler effect - Examples • car horn • sirens • radar gun • light – increase frequency – blue shift – decrease frequency – red shift