Atomic Physics Flashcards
What is Nuclear Fission?
When a large and unstable nucleus splits to form two smaller nuclei, neutrons and energy.
What is Nuclear Fusion?
When two small nuclei fuse to form a heavier nucleus and release energy.
Describe Alpha radiation
- 1 particle consists of 2 protons and 2 neutrons.
- Highly ionizing.
- Weakly penetrating.
- blocked by 5cm of air or a thin sheet of paper.
Alpha particle equation
4^2v a
Describe beta radiation
- 1 particle consists of a single electron.
- Medium ionising effect.
- Medium penetration.
- Blocked by 50cm of air or a sheet or metal.
Beta particle equation
B^0v-1
Describe y (gamma) radiation
- Weakly ionizing
- Highly penetrating
- blocked by several cm of lead
- Electromagnetic radiation ( no particles )
y ( gamma ) particle equation.
y^0v0
gamma radiation is an electromagnetic wave
How is alpha, beta and gamma affected by electric and magnetic fields??
Alpha is slightly deflected.
Beta is greatly deflected, in the opposite direction to alpha radiation.
Gamma is not deflected.
How can radiation be detected?
- how do they work
- Photographic film: The film is white; as it absorbs radiation it darkens.
- Cloud chamber: It is a container filled with water vapor. Ionizing radiation causes the vapor to condense, forming tracks. ( Alpha particle being short and Beta particle being long )
- Geiger Muller tubes: They are tubes which transmit an electric pulse every time radiation is absorbed, producing a clicking sound.
What is background radiation? Give some sources.
Weak radiation from external sources which is always present.
Sources:
- Cosmic rays
- Radiation from rocks
- Nuclear fallout
- Medical rays
Define half life
Half life is the time taken for the number of radioactive nuclei to halve.
Give 3 practical applications of radioactive materials.
- Smoke alarms
- Medical tracers
- Radiotherapy
What kind of radiation is used in smoke detectors? How do they work.
Alpha radiation.
Alpha radiation is emitted into the air, reaching a detector it completes the circuit. If smoke is present, it blocks alpha radiation so it doesn’t reach the detector and the circuit is broken causing an alarm to sound.
Use of beta emitters? How does it work?
Thickness monitoring of metal sheets.
A source & receiver are placed on either side of the sheet. If there is a drop or rise in the number of particles detected, the thickness has changed and needs adjusting.
