P2 - Radioactivity
- Created by: EllenMIW
- Created on: 19-12-15 14:45
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- Radicoactivity - P2
- Types of radiation
- Alpha
- 2 protons, 2 neutrons (like He nucleus)
- +2 relative charge
- Relative mass 4
- Low penetrating ability
- Stopped by paper/skin
- Few centimeters in air
- Strog ionising ability
- Deflected by electric field and magnetic field
- Smoke detector
- Beta
- Electron
- -1 relative charge
- Negligible relative mass
- Moderate penetrating ability
- Stopped by aluminium
- Several centimeters in air
- Moderate ionising ability
- Deflected by electric and magnetic field
- Thickness gauging
- Gamma rays
- Electromagnetic wave
- 0 relative charge
- 0 relative mass
- High penetrating ability
- Never stopped; reduced by thick lead
- Weak ionising ability
- Not deflected by electric or magnetic field
- Sterilisation, tracing
- Alpha
- Background radiation
- Radiation all around us
- 42% from radon gas
- Istopes
- Different numbers of neutrons
- Rutherford's experiment
- Vacuum so alpha could travel
- Thin gold foil bombarded with alpha
- Most straight through, some deflected slightly, 1 in 8000 bounced back
- Only explained by presence of tiny nucleus with most of mass
- Half life
- The time it takes for the number of atoms of the isotope to halve
- Exponential decay curve
- Activity of a radioactive substance
- The number of atoms that decay per second
- Nuclear fission
- Neutron absorbed, splits into 2 nuclei
- Large amount of energy released, new atoms are radioactive
- Gamma radiation and kinetic energy
- Large amount of energy released, new atoms are radioactive
- Fission fragments
- Control rods control reaction
- Moderator slows neutrons in uranium fueled reactor
- Uranium -235 or plutonium -239
- Neutron absorbed, splits into 2 nuclei
- Nuclear fusion
- 2 hydrogen nuclei collide and fuse to form a helium nucleus
- Gas in reactor heated by passing electric current through it
- Forms plasma of small nuclei
- Contained using magnetic field to stop touching walls
- Forms plasma of small nuclei
- Better than fission
- Short half life of waste
- No danger of reactor going into meltdown
- Chernobyl 1986, nuclear reactor explosion
- Early Universe
- Cools as expands
- Less than 2 mins after big bang, quarks, electrons, protons and neutrons formed
- After 100,000 years, atoms formed (radiation)
- A few billion years later, gravity caused galaxies
- Life of a star
- Nebula drawn together by gravity into protostar
- Denser and hotter = nuclear fusion= star
- Stable as force of gravity = radiation pressure
- Runs out of hydrogen
- Stars like Sun
- Expand and cool to red giant
- Heavier elements fused in core
- Shrinks and heats to white dwarf
- Cools into black dwarf
- Shrinks and heats to white dwarf
- Heavier elements fused in core
- Expand and cool to red giant
- Larger stars
- Expand to supergiants
- Explode in supernova
- Core compressed to neutron star or black hole
- Forms elements heavier than iron
- Explode in supernova
- Expand to supergiants
- Stars like Sun
- Runs out of hydrogen
- Stable as force of gravity = radiation pressure
- Denser and hotter = nuclear fusion= star
- Nebula drawn together by gravity into protostar
- Types of radiation
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