Zusammenfassung der Ressource
Radiation and Half-Life
- Detecting Ionising Radiation
- Photographic film
- Becquerel (Bq) - unit of radioactivity
- Measures how many unstable nuclei disintegrating in one second
- Geiger-Muller Tube
- Detects radiation
- Background Radiation
- What
- Low level ionising radiation
- Produced all the time E.G. ground and buildings, radon, medical, etc.
- Natural background radiation from Earth
- Radon, thoron
- Build up in basements and foundations of buildings
- Natural background radiation from space
- Cosmic rays from exploding stars called supernovae or given by Sun
- Internal radiation
- Atoms making up bodies formed in violent reactions in beginning of Universe
- Some atoms radioactive so we carry radiation
- When breath in, take in tiny amounts of carbon-14 so renew amount of radioactive carbon in bodies
- Artificial radiation
- Generating electricity in nuclear power stations has leaked radioactive material in environment
- Testing nuclear weapons in atmosphere increase no of radioactive isotopes on Earth
- Radioactive tracers in industry and medicine
- Radioactive Decay
- What
- Random process
- Nucleus of an unstable atom loses energy by emitting radiation, including alpha particles, beta
particles, gamma rays.
- Exponential decay
- The smaller the quantity, the more slowly the quantity decreases
- Rate of decay would fall as time passes because fewer nuclei to decay
- Half-Life
- What
- Average time taken for half the original mass of the sample to decay
- Different for different radioactive isotopes
- Measuring half-life
- Use GM tube
- Rate of decay, corrected for background radiation, proportional to amount of radioactive isotope present
- Isotopes with short half lives used for medical purposes
- Isotopes with long half lives used for dating samples of organic material