Progressive waves

• Amplitude is the maximum displacement from the undisturbed position.
• The distance between wave peaks is the wavelength
• frequency is the number of cycles per second ,measured in hertz.
• period is the time for one complete cycle measured in seconds.
• the speed of light is 3x10^8 m/s
• the speed of sound is 330 m/s
• frequency is equal to 1/ the time period
• waves have different measures of phase . At equilibrium it is the values 0 ,180 and 360 (one cycle). At positive max peak it is 90. At negative max peak it is 270. This can also be converted to radians.
• 1. In phase is when phase difference is equal to 0 pie radians
  2. Out of phase is when phase difference of pie/4 radians
  3. in anti-phase difference of pie radians
• There are two equations to find phase difference:

  1. 2pie x change in time / time period
  2. 2pie x change in displacement / wavelength
• Transverse is where oscillations are perpendicular to the direction of energy propagation

  Longitudinal is where the oscillations are parallel to the direction of energy transfer.
• Electromagnetic waves is a spectrum of light (hence travels at speed of light) where energy is oscillated in electric and magnetic fields.
• polarization oscillations occur only in one direction perpendicular to the direction of wave propagation.
• only transverse waves can be polarized as they oscillate in any plane perpendicular to the propagation direction.
• polarization restricts oscillations to one direction , these oscillations will still be perpendicular to direction of energy propagation.
• light can be polarized through reflection , refraction and scattering.
• examples of polarization are sunglasses and aerials;

  • sunglasses contain a polarizing filter which filters direction of light reducing glare.
  • aerials have rods along the side which only allow the reception of signals the same plane