Flashcards
Physics
Flashcards do conjunto (10)
- 1Physics: Radioactivity/RadiationRadioactive Elements/atoms
- a radioactive atom is where the protons and neutrons in nucleus are unstable and disintegrate emitting alpha - 2The Atom - All matter is made from atoms - inside every atom there are protons, neutrons and electronsCharge of a proton= +1
Charge of a neutron= 0
Charge of an electron= -1 - 3Mass of a proton= 1 Mass of a neutron=1 Mass of an electron= 1/1840Position of a proton= nucleus
Position of a neutron= nucleus
Position of an electron= shell - 4Alpha Radiation - positively charged helium nuclei with a relative mass of 4, relative charge of +2, range in air of 2-4 cm and can be stopped by thin paper.Beta Radiation
- fast electrons with a relative mass of 1/1840, relative charge of -1, range in air of several metres and can be stopped by about 5 mm aluminium. - 5Gamma Radiation - electromagnetic wave of high energy with a relative mass of 0, relative charge of 0, unlimited range in air but gets weaker the further it travels and thick lead can absorb most of it but may not stop it completely.Half - Life
- time taken for the level of radioactivity to fall by half.
- the unit of radioactivity in Becquerel (Bq)
- radioactive decay is random - 6Background Radiation - radiation all around us from natural and artificial sources. - radiation is ionising and can damage living cells and can cause cancer. - Alpha is the most ionising.Sources of background radiation
- Carbon-14 a type of carbon found inside all living organisms.
- radon, emitted from granite rocks.
- traces of potassium found in some foods.
- waste products from nuclear power stations. - 7Uses of Radiation - used to kill cancerous cells. - used in surgical examinationsWhich half - life is best for a surgical examination?
- 7 hours as it is long enough to carry out the procedure but will decay before it can do harm to the body. 20 mins is too short and 24 days is too - it could cause harm to body in this time. - 8Which type of radiation would you not choose for a medical examination? - Alpha as it is the most ionising and would cause the most damage inside the body.Which type of radiation is used to keep food fresh?
- Gamma is used to kill bacteria on fruit. This keeps the fruit fresher for longer.
- Gamma is used instead of Alpha or Beta as it can penetrate through the fruit containers. - 9Ionisation - charged atoms are called ions and the process of turning neutral atoms into charged atoms is called ionisation. - this is why Alpha, Beta & Gamma are called ionising radiationIonising Radiation
- radioactivity is the emission of ionising radiation.
- ionising radiation means that atoms become ions (charged particles)
- Alpha & Beta particles and Gamma waves collide with atoms as they pass through a material.
- they are most likely to collide with one of the electrons that are orbiting the nucleus. - 10Ionising Radiation (cont.) - remember that an atom has a neutral charge, so when a collision is made with one of the electrons this causes the electron to be removed and the atom becomes a positively charged ion.
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- GCSE Physics FlashCards sobre Physics , criado por eimhear quigley em 29-03-2017.
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- eimhear quigley
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