Waves

Waves

1. Basics

   • An OSCILLATION is a repeated pattern
     • A WAVE is an oscillation that travels from one place to another
   • Most waves travel through a medium. The medium does not move but the oscillations move through it.
   • COMPRESSION - The waves are compressed
   • RAREFACTION - The waves are spread out
   • Longitudinal waves- oscillations are parallel to the direction of energy transfer
   • Transverse waves - oscillations are perpendicular to the direction of energy transfer

2. Equations

   • time (seconds) = 1/frequency (hertz)
   • speed= frequency x wavelength
   • lambda = wavelength

3. Electromagnetic Spectrum

   • transverse waves made up of electric and magnetic fields
   • They all have the same speed. In a vacuum it is 300,000,000 m/s
   • They all carry different amounts of energy
   • The higher the energy, the higher it's frequency, the shorter it's wavelength
     • Gamma rays are very dangerous and ionising because the have the highest amount of energy
   • I freflected,
   • When they hit a surface they can be absorbed, transmitted, or reflected depending on the wave. E.g. light waves are reflected by the skin, but x rays are transmitted through
   • Radio waves
     • radio and TV signals
   • Microwaves
     • cooking, mobile phones
   • infared
     • toasters, optical fibres, remote controls
   • Visable light
     • To see things
       • In CD and DVD players the light is reflected from tiny pits in the disk. The pattern is detected and translated into sound or data
   • Ultra violet
     • sunbeds, flourecent lights, security pens
   • Xrays
     • medical, industry
   • Gamma Rays
     • kill ; cancer, bacteria and to sterillise.

4. Ultra sound

   • Anything above 200,000 HZ
   • Non ionising
   • Used predominantly for pre-natal scanning

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