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P2.6.3 - P2.6.4
Types of Radiation
|What does alpha emit?
|2 protons and 2 neutrons
|How do the atomic and mass numbers change after alpha radiation has been emitted?
|The atomic number decreases by 2, the mass number decreases by 4
|Name three features of alpha radiation
|Very ionising, Small level of penetration, Can be deflected by a magnetic or electric fields (in the opposite direction to beta)
|Name 3 things that can stop alpha radiation
|Skin, 1mm of paper, 5cm of air
|What does beta emit?
|A neutron turns into a proton and an electron, the electron is emitted and the proton stays in the nucleus
|How do the atomic and mass numbers change after beta radiation has been emitted
|The atomic number increases by 1, the mass number stays the same
|Name three features of beta radiation
|Less ionising than alpha, Penetrates further than alpha, Can be deflected by a magnetic or electric fields (in the opposite direction to alpha)
|Name 2 things that can stop beta radiation
|5mm of Aluminium, 1m of Air
|What is gamma radiation?
|An electromagnetic wave that is emitted from the nucleus
|How does the nucleus change when gamma radiation is emitted?
|It stays the same
|Name three features of gamma radiation
|Weakly ionising, Very high penetration Cannot be deflected by a magnetic field
|Name 2 things that can stop gamma radiation
|1m of concrete, 5-7cm of lead
|What is alpha radiation used for?
|Smoke alarms. Poorly penetrating particles therefore not dangerous. Needs a half-life of several years
|What is beta radiation used for?
|Thickness monitoring - manufacture of paper. Alpha particles would be stopped by a thin sheet of paper and gamma rays would pass straight through it. Needs a half-life of many years so that decreases in count rate are due to the thickness of the paper.
|What is gamma (and beta) radiation used for?
|Tracers in medicine. The source is injected or swallowed by the patient. Its progress around the body is monitored by a detector outside the patient's body. Needs a half-life of a few hours so the patient isn't exposed to unnecessary radioactivity.
|What is half-life?
|The time taken for the number of unstable nuclei in a sample to halve.