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Science presenter Jon Chase explains some of the uses of radioactivity and how unstable nuclei decay release ionising radiation

  1. count rate Measure of the amount of radiation reaching a detector in a given time, usually shown as counts per second or counts per minute.
  2. deflected Objects that change direction because of a force are said to be deflected. For example, alpha and beta particles are electrically charged - they are deflected by electric and magnetic fields.
  3. electric field Area surrounding an electric charge that may influence other charged particles.
  4. electromagnetic radiation Energy travelling as waves in the form of changing electrical and magnetic fields.
  5. electron Sub-atomic particle, with a negative charge and a negligible mass relative to protons and neutrons.
  6. field The region in which a force may affect an object. For example, a magnetic field around a magnet can be detected using iron filings or plotting compasses, but is invisible to us.
  7. force A push or a pull. The unit of force is the newton (N).
  8. frequency The number of waves produced each second. The unit of frequency is Hertz, Hz.
  9. ionising radiation Radiation that is able to remove electrons from atoms or molecules to produce positively-charged particles called ions.
  10. isotope Atoms of an element with the same number of protons and electrons but different numbers of neutrons.
  11. motion Movement.
  12. neutral An object that does not have a positive or negative charge.
  13. neutron Uncharged sub-atomic particle, with a mass of 1 relative to a proton.
  14. nucleus The central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. The plural of nucleus is nuclei.
  15. periodic table A tabular representation of all known elements in order based on atomic number, eg all the noble gases are found on the right of the periodic table.
  16. plate A surface, often flat.
  17. proton Sub-atomic particle with a positive charge and a relative mass of 1.
  18. radiation Energy carried by particles from a radioactive substance, or spreading out from a source.
  19. radioactive atoms Atoms that have unstable nuclei that can break apart or change, releasing radiation.
  20. wavelength The length of a single wave, measured from one wave crest to the next.