Radioactivity and Particles Flashcards
(20 cards)
1
Q
What is alpha radiation?
A
- Releases Helium nucleus with a charge of +2e, consisting of 2 protons and 2 neutrons.
- The most ionising radiation
- Low penetration: range of a few centimeters in air
- Stopped by paper
- Used in paper thickness monitoring and smoke detectors
2
Q
What is beta radiation?
A
- Releases fast electron with a charge of -e
- Formed when a neutron decays into a proton and an electron
- Quite ionising
- Medium penetration: range of up to 1 meter in air
- Stopped by several millimetres of aluminium
- Used in aluminium thickness monitoring (i.e. factories)
3
Q
What is gamma radiation?
A
- High energy electromagnetic radiation from the nucleus
- The least ionising
- Most penetrating: is significantly reduced (not stopped) by several centimetres of lead
- Used in medical and industrial tracing and sterilisation
4
Q
What are isotopes of the same element?
A
- Same number of protons but a different number of neutrons
5
Q
What is radioactivity?
A
- The process of ionising radiation being emitted from unstable nuclei in a random manner
6
Q
What is atomic number?
A
- The number of protons in the nucleus of an atom
7
Q
What is mass number?
A
- The total number of nucleons (protons + neutrons) in a nucleus
8
Q
What is background radiation?
A
- Ionising radiation from Earth and space, including rocks, radon gas, food (e.g. bananas), and cosmic rays.
9
Q
What is activity in radioactivity?
A
- The number of decays per second
- Measured in Becquerels (Bq)
10
Q
What is half-life?
A
- The time taken for the remaining number of radioactive nuclei to halve
11
Q
What is contamination?
A
- The presence of radioisotopes ingested or existing within a substance or body that continue to decay
12
Q
What is irradiation?
A
- When a substance or body is exposed to radiation from a source but is not in contact with the source itself
13
Q
What is radioactive waste?
A
- Waste that is stored in sealed containers capable of containing radioactivity for long periods
14
Q
What is fission?
A
- The splitting of an unstable nucleus into smaller, more stable nuclei and neutrons, converting mass into energy
15
Q
What happens during U-235 fission?
A
- U-235 absorbs a neutron to become U-236, which is unstable
- It fissions, releasing energy as kinetic energy of daughter nuclei and neutrons, causing a chain reaction
16
Q
What are control rods?
A
- Devices that slow a chain reaction by absorbing neutrons
- Can be adjusted
17
Q
What is a moderator in nuclear reactions?
A
- A substance that slows fission neutrons to increase the likelihood of absorption by U-235 nuclei
- e.g. water
18
Q
What is fusion?
A
- The joining of nuclei into larger, more stable nuclei
- Converting mass into energy
- Released as kinetic energy of fusion products
- Source of energy in stars
19
Q
What conditions are needed for fusion?
A
- High temperatures and pressures are required
- In order to overcome the repulsion between protons due to their like charges
20
Q
What device can detect ionising radiations?
A
- Geiger-Muller tube
