Waves - W01 - W05

• What is a longitudinal wave

  The plane of oscillation of the particle is parallel to the direction of the propagation (energy transfer)

  • e.g. sound Waves, p waves
• Longitudinal waves transfer energy through compression and rarefraction of the waves
• What is a transverse wave


  the plane of oscillation of the particles is perpendicular to the direction of propagation

  • e.g. EM waves
• What is a progressive wave

  A progressive wave is an oscillation that transfers energy but not matter
• What is amplitude


  It is the max displacement from equilibrium
• What is wavelength


  It Is the shortest distance between two points in phase
• What is time period

  It is the time taken for one complete oscillation
• What is frequency


  It is the number of cycles per second
• frequency equations 


  F = v/wavelength

  F = 1/T
• About a polarised wave

  -a polarised wave is a wave limited to one perpendicular plane of oscillation

  -longitudinal waves cannot, therefore, be polarised

  -crossed polarisers will completely block a transverse wave

  -Polaroid glass —> light metal grid —> microwaves
• Polarisation summary


  -only transverse waves can be polarised as they oscillate in all planes perpendicular to the direction of energy transfer

  -longitudinal waves cannot be polarised as they oscillate parallel to the direction of propagation

  -polarisation limits transverse waves to a single perpendicular plane of oscillation which is coplanar with its direction of propagation

  -crossed Polaroids block transverse waves

  -a metal grid can be used to polarise microwaves
• What is meant by particles in phase

  It is when two particles from two waves are moving the same direction at all times
• What is meant by phase difference

  It is the difference in phase of two parts of the wave cycle - degrees
• What is superposition


  When two waves overlap they superpose. This means a new wave is formed whose displacemnt at any point = sum of the displacements of the two waves
• How is a stationary wave formed on a cord

  -two progressive waves travelling in opposite directions(often due to reflection)

  -with the same wavelength or similar amplitude

  -will superposition to form a standing wave

  -they don’t transfer energy or matter
• What is a node and antinode

  Node = point of min amplitude (.)

  antinode = point of max amplitude (x)