Wave Velocity and Interaction

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Wave Velocity and Interaction
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Wave Velocity

• determined by the frequency AND the wavelength
• in a given medium, the speed of a wave stays the
  same
• sound travels around 770 mph in air, 2260 mph in
  helium, 3,320 mph in water and 13,350 mph in
  steel
• the speed of a wave depends upon the elasticity
  and density of the medium it is traveling through

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Wave velocity formula
v f x ?
v velocity (wave speed) f frequency (how many
waves that pass a point in a given time) ?
wavelength
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Which wave is faster if three wavelengths pass
here in one second?
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Example problem

• What is the speed of a wave with a frequency of 5
  Hz and a wavelength of 3 meters?

given formula
set up problem answer w/ unit of
measurement
f 5 Hz v f(?) 5Hz (3m)
15 m/s ? 3 m
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Interactions of Waves

• 1. Reflection
• a wave bounces back after hitting a boundary
• the law of reflection states that the angle of
  incidence is equal to the angle of reflection
• mean that a wave will bounce off a boundary at
  the same angle that it came in at

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• 2. Refraction
• the bending of waves due to a change of speed
• as a wave passes from one material to another,
  they may change speed

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• 3. Interference
• results as two or more waves arrive at the same
  place at the same time
• constructive interference
• combining two waves to make a bigger wave

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• destructive interference
• two waves combine and make a smaller wave or none
  at all

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• Standing Waves
• looks like a wave that is not moving
• very important in musical instruments

http//www1.union.edu/malekis/PhysDemoClips/Stand
ingWaveMovie.mov