Waves

Waves

1. Longitudinal

   • Sound waves
   • Primary Seismic Waves
   • Compression Waves
   • Waves in which the direction of vibration of the particles is parallel to the direction in which the waves travel.

2. Transverse

   • Waves in which the direction of vibration is perpendicular to the direction in which the wave travels.
   • Electromagnetic waves
   • Secondary seismic Waves
   • Waves on a string or wire

3. Polarisation

   • Transverse can be plane-polarised if vibrations stay in one plane only.
   • Longitudinal cannot be polarised.
   • Light from a filament lamp or candle is unpolarised.
   • Light can be polarised if passed through polaroid filter, as it allows light to to vibrate in a certain direction.
   • If there are 2 filters light intensity can be minimum if 1 filter is 90 degrees to the other, which stops light passing through.

4. Key Terms

   • displacement- distance and direction of a vibrating particle from its equilibrium point
   • amplitude- a waves maximum displacement
   • wavelength- the least distance between 2 adjacent vibrating particles
   • frequency- number of cycles of vibration of a particle per second
   • period- time for a complete wave to pass a fixed point
   • One complete cycle- from maximum displacement to the next
   • phase difference- fraction of a cycle between the vibrations of 2 vibrating particles