Properties of EM Waves

• Properties of EM Waves

  • Electromagnetic waves are defined as:Transverse waves that transfer energy from the source of the waves to an absorber
  • All electromagnetic waves share the following properties:
  • They are all transverse
  • They can all travel through a vacuum
  • They all travel at the same speed in a vacuum
  • There are 7 types of electromagnetic waves, which all together form a continuous spectrum called the Electromagnetic spectrum
• Transfer of Energy by EM Waves

  • Electromagnetic (EM) waves carry energy and so can transfer energy from one point to another point
  • This is from a source to an absorber
  • E.g. From the sun to our skin
  • EM waves with a shorter wavelength carry a higher energy
  • This includes UV, X-rays and gamma rays
  • The higher the energy of the EM wave, the more dangerous it is
• Energy Transfer by Microwaves

  • Water molecules absorb certain wavelengths of microwave radiation
  • Therefore, microwave ovens transfer energy from the electronics to heat the food placed inside it
• Energy transfer in a microwave oven

  
• Energy Transfer by Infrared

  • All hot objects emit infrared radiation
  • The emitted waves can then be absorbed by other objects, warming them up

  Energy Transfers from the Sun

  • The Sun emits several types of EM radiation, including:
  • Visible light waves allow living creatures to see
  • Infrared waves heat up the Earth
  • Ultraviolet waves provide plants with the energy for photosynthesis which they need to grow