Properties of waves 2

• What happens when electromagnetic waves are generated or absorbed?

  Changes take place in atoms or in the nuclei of atoms.
• What happens when we heat atoms?

  We cause electrons to move from one energy level to a higher one, when this electron returns to its original energy level, it generates an electromagnetic wave (e.g. light). So a change to the atom has generated an electromagnetic wave.
• Electromagnetic waves can be generated by what?

  A change to the nucleus e.g. gamma rays. Gamma rays can be emitted from the nucleus of radioactive atoms. Once the gamma ray has been emitted, the nucleus has less energy than it had at the start.
• What happens when electromagnetic waves are absorbed or emitted?

  Absorbed- It can cause changes to atoms e.g. electrons can change energy levels.

  Emitted/absorbed- Electromagnetic waves can be emitted and absorbed over a wide frequency range from radiowaves to gamma rays.
• What are the hazards of electromagnetic radiation?

  Ultraviolet waves, x-rays and gamma rays are potentially very hazardous to the human body.

  UV- Increase the risk of skin cancer and cause the skin to age prematurely.

  X-rays/gamma rays- Both are ionising radiation, meaning they knock electrons off atoms when they are absorbed. This means they cause the mutation of genes and this increases the risk of cancer.
• What does the damage of radiation depend on?

  The type of radiation

  The dose of radiation

  The area of the body exposed to it.
• What is the dose of radiation measured in?

  Sieverts (Sv) or Millisieverts (mSv)
• How can radiowaves be produced?

  When electrons oscillate in electrical circuits, these radiowaves can be absorbed, for example, by an electrical circuit in an aerial. When this happens, they now cause electrons in the circuit to oscillate. This can create an alternating current with the same frequency as the radiowaves.