Topic 7 - Radioactivty and particals Flashcards
What is alpha?
particle
- is a helium nucleus, two protons and two neutrons. It has a large mass, compared to other ionising radiations, and a strong positive charge.
What is beta?
particle
- is a fast moving electron. It has a very small mass and a negative charge.
What is gamma?
is a high-energy electromagnetic wave.
Gamma rays
are caused by changes within the nucleus. They are part of the
electromagnetic spectrum
and so travel at the speed of light. They have no mass and no charge.
Alpha range of absorption?
3-5cm
beta range of absorption?
15cm
gamma range of absorption?
very far
alpha ionising power?
high
beta ionising power?
medium
gamma ionising power?
little
Can pass through paper? alpha
no
Can pass through paper? beta
yes
Can pass through paper? gamma
yes
Can pass through 5mm of aluminium - alpha
no
Can pass through 5mm of aluminium - beta
no
Can pass through 5mm of aluminium - gamma
yes
Can pass through 5cm of lead? alpha
no
Can pass through 5cm of lead? beta
no
Can pass through 5cm of lead? gamma
no
Speed - alpha
slow
Speed - beta
medium
Speed - gamma
fast
what is a half life?
the time required for a quantity (of substance) to reduce to half of its initial value.
uses of radioactivity? (6)
Food irradiation
Gauging and Thickness control
Tracers in medicine and in industry
Radiotherapy
Smoke detectors
Radioactive dating
measure of radioactivity?
Becquerel (Bq).
Nuclear fusion?
Nuclear fusion is when two small, light nuclei join together to make one heavier nucleus and become more stable. Fusion reactions occur in stars where, for example, two hydrogen nuclei fuse together under high temperatures and pressure to form a nucleus of a helium isotope.
Nuclear fission?
The splitting of a large nucleus to produce two daugther nuclei. Two or three neutrons are also released in the process. The energy from the neutrons powers a nuclear reactor.
Similarities of nuclear fission and fusion? (2)
- Both have a change in the nuclei
- Both release energy
differances of nuclear fission and fusion? (2)
- Fusion involves the smallest nuclei coming together to make a larger nucleus.
- Fission involves the largest nuclei splitting into two smaller nuclei
Where nuclear fusion happens:
Fusion only occurs here naturally because of the extremely high temperature and pressure. This is required because the nuclei are both positively charged.
