Dangers of Electromagnetic Waves (Cambridge International IGCSE Physics)

Spec point — 3.3.3 · Describe the harmful effects on people of excessive exposure to electromagnetic radiation, including: (a) microwaves; internal heating of body cells (b) infrared; skin burns (c) ultraviolet; damage to surface cells and eyes, leading to skin cancer and eye conditions (d) X-rays and gamma rays; mutation or damage to cells in the body

Dangers of electromagnetic waves

• Excessive exposure to electromagnetic radiation has harmful effects on people

  • As the frequency of the electromagnetic (EM) waves increases, so does their energy

• Beyond the visible part of the spectrum (ultraviolet waves, X-rays and gamma rays), the energy is large enough to ionise atoms

  • The higher the frequency, the more ionising the radiation

• The effects of ionisation also depend on the type of radiation and the size of the dose

Harmful effects of EM radiation

Harmful effects of excessive microwave exposure

• Certain frequencies of microwaves are absorbed by water molecules

• Humans contain a lot of water, so there is a risk of internal heating from microwaves

• This might worry some people, but the longer wavelength (lower energy) microwaves used in everyday circumstances are proven to be safe

  • Microwaves used for communications (including mobile phones) emit very small amounts of energy which are not known to cause any harm
  • Microwave ovens, on the other hand, emit very large amounts of energy; however, that energy is prevented from escaping the oven by the metal walls and metal grid in the glass door

Harmful effects of excessive ultraviolet exposure

• Ultraviolet is similar to visible light, except it is invisible to the human eye and carries a much higher energy

• If eyes are exposed to high levels of UV it can cause severe eye damage

  • Good quality sunglasses will absorb ultraviolet, preventing it from entering the eyes

• Ultraviolet can kill cells or cause them to malfunction

  • This can cause premature ageing, and diseases such as skin cancer

• Sunscreen absorbs ultraviolet light, preventing it from damaging the skin

Harmful effects of excessive X-ray and gamma-ray exposure

• X-rays and gamma rays are the most ionising types of EM waves

  • They can penetrate the body and cause internal damage
  • They can cause the mutation of DNA, causing cancer