P2b
- Created by: anniedarlington
- Created on: 01-04-15 11:08
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- P2b
- fuses and earthing
- a fault allows live wire to touch metal case, a big current flows out through earth wire, a big surge in current blows the fuse, the device is isolated from the earth wire
- atomic structure
- Rutherford and Marsden
- fired a beam of alpha particles at some gold foil
- expected to see slightly deflected alpha particles by the electrons
- most went straight through, some came straight back, some deflected
- most of mass concentrated in tiny nucleus, nucleus must be positively charged, most of atom must be empty space
- Rutherford and Marsden
- background radiation
- dumped nuclear waste and nuclear weapons would add to this
- food
- half life
- always some background radiation, radioactivity will never fall to 0
- uses of radiation
- smoke detectors use alpha
- tracers in medicine always use short life beta or gamma
- radiotherapy uses gamma
- sterilisation of food and surgical instruments uses gamma
- nuclear fission and fusion
- fission forms lighter elements, uses uranium or plutonium (not hydrogen), radioactive waste is formed, and reactors already exist, all unlike fusion
- life cycle of stars
- gas and dust in orbit around a newly formed star may clump together to form masses which merge together to form planet
- stars become red giants because the hydrogen fuel begins to run out
- red giants are red because the surface cools
- fuses and earthing
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