Waves electromagnetism and space p12 - p16

• Waves can be used to transfer energy and information
• Transverse waves - waves that oscillate perpendicular to the direction of energy transfer
• Longitudinal waves - oscillations parallel to the direction of energy transfer (sound waves)
• Mechanical waves are waves that travel through a medium can be longitudinal or transverse
• Amplitude - The maximum displacement of a point from its equilibrium position.( hight from the middle line )
• Wavelength - the distance between two adjacent points on a wave.
• Frequency - the number of waves passing a point per second.
• Time period = 1/frequency (s)
• Wave speed = frequency x wavelength (m/s)
• Plane waves - in a ripple tank are reflected at the same angle as they were insidented as there speed and wavelength do not change
• Refraction occurs at a boundary at two materials because the speed and wavelength changes
• Sound waves - vibrations that travle or through a medium
• Sound waves cannot travel through a vacuum
• To investigate waves use

  • a ripple tank
  • a string
  • a single generator and a loud speaker
• The pitch increases the frequency
• The loudness of the note increases the amplitude
• Ultrasound waves are reflected and times to calculate distance
• Order of the earths layers :

  Crust

  mantle

  outer core

  inter core
• Primary waves (p-waves) cause initial tremors - these are longitudinal waves that push and pull materials
• Secondary waves ( s-waves ) cause more tremors than p waves they are transverse waves and travel faster than p waves
• L waves are the slowest and cause violent movment on the surface - they are both longitudinal and transverse
• Seismic waves - waves that travle thought the caused by earthquakes