topic p6- waves

• time period = 1 / frequency

  T = 1 / f
• wave basics

  • waves transfer energy in the direction they are travelling
  • all waves can be absorbed, transmitted or reflected
  • particles vibrate to transfer energy when waves pass through a medium
• wave speed = frequency x wavelength

  
• transverse

  
• transverse

  • have perpendicular vibrations to the direction of energy transfer
  • most waves are transverse, such as EM waves and water waves
• longitudinal

  • have parallel vibrations to the direction of energy transfer
  • examples include sound waves in air and seismic (shock) waves
• longitudinal

  
• refraction

  refraction occurs when waves change direction at a boundary between two mediums ~
• wave front diagrams

  
• refraction ~

  
• electromagnetic waves

  
• electromagnetic waves in the order of increasing frequency and decreasing wavelength

  • radio waves
  • microwaves
  • infra red
  • visible light
  • ultra violet
  • x-rays
  • gamma rays
• radio waves have the longest

  wavelength
• gamma rays have the highest

  frequency
• electromagnetic waves

  • EM waves are transverse waves that transfer energy from a source to an absorber
  • all EM waves travel the same speed through air or vacuum
  • the human eye can only detect the visible light portion
  • different EM waves have many different uses
• uses of EM waves- radio waves

  • radio communication
  • bluetooth
  • Tv
• uses of EM waves- microwaves

  • satellites
  • microwave ovens
• uses of EM waves- infra-red

  • monitor temperature
  • thermal cameras
  • heaters
• uses of EM waves- visible light

  • fibre optics (carry data)
• uses of EM waves- ultra violet

  • sun tan
  • invisible pens
  • fluorescent lights
• uses of EM waves- x-rays

  • medicine in radiography
• uses of EM waves- gamma rays

  • medical tracers
• dangers of EM waves

  • radiation risk can be measured using the dose Sieverts
  • high frequency waves transfer lots of energy so can be harmful- UV, x-rays and gamma rays
  • low frequency waves such as radio waves don't transfer much and pass through soft tissue without absorption
  • UV radiation damages surface cells which leads to sunburn and could increase chances of skin cancer