Waves and the electromagnetic spectrum

Waves and the electromagnetic spectrum

1. Wavelength- distance between two adjacent peaks or troughs

   • Amplitude- size of wave oscillations
   • wavefront= moving line which joins all points on crest of a wave

2. Longitudinal waves consist of compressions and rarefactions

   • compressions- squashed up particles
   • rarefaction- spread out particles
   • e.g. sound waves

3. Echoes- waves reflected off a surface

   • when a wave enters a new medium it is refracted
   • When a wavefront goes through a gap it changes shape and is diffracted
     • small gap= lots of diffraction
       • same sized aperture= most diffraction
     • large gap= less diffraction

4. wave speed= frequency x wavelength

   • F=1/t
   • t= 1/f

5. Transfer information without transferring matter

6. electromagnetic wave= wave that transfers energy

   • spectrum= electromagnetic waves ordered according to wavelength and frequency
     • radiowaves
       • Microwaves
         • IR radiation
           • Visible light
             • UV
               • X-rays
                 • Gamma rays
                   • sterilising food and medical equipment
                     • cancer, cell mutation
                 • medical uses- observing internal structures of objects
               • sterilisation and fluorescent light
                 • blindness and damage to surface cells
             • optical fibres and photography
           • heating and night-vision
             • skin burns
         • cooking and satellite transmissions
           • internal heating of body tissues
       • Broadcasting and communications