Waves

Waves

1. Types

   • Transverse
     • The oscillation is perpendicular to the energy transfer.
       • e.g. Light.
   • Longitudinal
     • The oscillation is parallel to the energy transfer.
       • e.g. Sound.
   • Electromagnetic
     • Can travel through anything (i.e. vacuums).
   • Mechanical
     • Requires matter to exist.
   • • Wave Length
       • The distance between two equal points.
     • Amplitude
       • Represents the energy.
     • Hertz (Hz)
       • Waves per second (frequency)

2. Equations

   • Wave Speed = Frequency x Wave length
     • m/sec = Hz x m

3. Properties

   • Reflection
     • Angle of incidence = angle of reflection.
   • Refraction
     • Waves change direction when crossing between different media.
       • This is because the light ray enters the block earlier on one side meaning that this side slows.
       • Into higher densities, the light slows.
   • Diffraction
     • When the waves spread out after passing through a gap.
     • Perfect diffraction occurs when the gap is the same size as the wavelength.
       • This will produce a semicircular pattern.

4. Doppler Effect

   • When the sound source is moving away...
     • The pitch lowers.
     • The wavelength increases.
     • The frequency decreases.
   • When the sound source is moving closer...
     • The pitch rises.
     • The frequency increases.
     • The wavelength decreases.
     • Position alone has no impact.

5. Red-Shift

   • Light from distant stars/galaxies is shifted towards the red end of the spectrum due to a longer wavelength.
     • This shows that the star/galaxy is moving away.
     • The further away the star/galaxy is, the greater the red-shift.
   • Proves that the universe is expanding.

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