risks and benefits of electromagnetic radiation

• Order of the electromagnetic spectrum in order of increasing wavelength

  • Gamma, X Ray, UV, Visible, Infrared, Microwaves, Radio
• Highest frequency electromagnetic wave

  Gamma waves
• Highest energy electromagnetic wave

  Gamma waves
• Properties shared by all electromagnetic waves

  • They are all transverse waves
  • They all travel at the same speed (3x10⁸ m/s)
  • They can travel through a vacuum
• Wave


  Transmits energy from source to absorber
• Range of frequencies of electromagnetic waves detected by the human eye


  400-700 nanometres
• What can happen when radiation strikes an object


  • Transmitted
  • Reflected
  • Absorbed
• Effect of absorbing high energy radiation

  Ionisation (the removal of electrons from atoms/molecules)
• Electron arrangement in atoms

  Electrons are found in 'energy levels' or 'shells' at different distances from the nucleus
• Effect of electromagnetic radiation on electron arrangement


  Absorption or emission of electromagnetic radiation can cause electron arrangement to change. (It can remove electrons from the atom or move electrons further from the nucleus)
• How atoms become ions

  By losing an outer electron
• Effects of body cells absorbing radiation

  Large amounts can damage cells. Smaller amounts cause mutation, causing cells to divide rapidly, which can lead to cancer.
• Source of gamma rays

  The nuclei of atoms
• Emission when electrons in atoms lose energy

  X rays, UV and visible light
• Types of radiation that can cause ionisation

  • Gamma, X-rays and high energy UV (as these have sufficient energy)
• Interaction of atmospheric oxygen with ultraviolet radiation


  Produces ozone
• Function of atmospheric ozone


  Ozone absorbs UV radiation from the sun, protecting the Earth and living organisms from harmful rays
• Interaction of infrared radiation with molecules


  It is emitted and absorbed by molecules
• Effect of UV radiation on body tissue

  UV radiation can cause cancer when skin is exposed to it. It can cause blindness if eyes are overexposed to UV radiation.
• Effect of X-rays on body tissue

  1. rays are ionising so they can damage or kill cells and cause mutations that could lead to cancer
• Effect of gamma rays on body tissue

  Gamma rays are even more ionising than X-rays, so they can cause cell mutations (which can lead to cancer) and cell death
• Production of radio waves (Higher)

  When there is an oscillating current in an electrical circuit
• Detection of radio waves (Higher)

  When the waves cause an oscillating current in a conductor
• Use of radio waves


  Communications, because radio waves are long wavelength and can travel long distances without losing quality
• Use of microwaves


  Cooking, as microwaves are absorbed by and heat fat/water in foods
• Uses of infrared radiation

  Cooking food (as it transfers thermal energy) infrared cameras, short range communication
• Uses of visible radiation


  Illuminating (i.e. seeing) and fibre optics, as they reflect best in glass (other waves have wavelengths that are too long/short)
• Uses of UV radiation

  Sterilisation, as it kills bacteria, energy efficient lamps, as it radiates low heat but high energy, and sun tanning etc.
• Uses of X-rays


  Medical imaging and treatment, because they are very high energy and can easily penetrate body tissues
• Uses of gamma rays


  Gamma rays are used in medical treatments, such as radiotherapy in the treatment of cancer