Radiation Flashcards
What are the 3 ionising radiations?
- Alpha
- Beta
- Gamma
Which radiation is the least penetrating?
Alpha
Which radiation is the most ionising?
Alpha
What are atoms composed of?
- Electrons (negative)
- Nucleus (positive)
- Protons (positive)
- Neutron (neutral)
What is the charge of an electron?
Negative
What is the charge of a proton?
Positive
What is the charge of a nucleus?
Positive
What is the charge of a neutron?
Positive
How are Ions made?
Ions are made when an electron is removed or added from an atom.
How do you create a positive Ion?
Positive Ions are made by removing an electron or more than one electron.
How do you create a negative Ion?
Negative Ions are made by adding an electron or more than one electron.
What is Alpha absorbed by?
A few cm of paper.
Which radiation is absorbed by a few cm of paper?
Alpha
What is Alpha?
Alpha is a Helium nucleus (2 protons 2 neutrons)
Which radiation is the slowest?
Alpha
Which radiation is the most ionising?
Alpha
Which radiation is the most biologically damaging?
Alpha
Which radiation is the middle penetrating?
Beta
Which radiation is the middle ionising?
Beta
Which radiation is absorbed by a few mm of Aluminium or dense material?
Beta
What is Beta absorbed by?
- A few mm of Aluminium
* Dense material
What is Beta?
Beta is a negatively charged electron ejected from a nucleus.
Which radiation has no mass and no charge?
Gamma
Which radiation is the most penetrating?
Gamma
What speed does Gamma travel at?
The speed of light (3.0x10^8ms^-1)
Why does Gamma have no mass?
Gamma is an EM wave.
Which radiation is an EM wave?
Gamma
Which radiation is absorbed by a few cm of lead or many metres of concrete?
Gamma
What is Gamma absorbed by?
- A few cm of lead
* Many metres of concrete
What is “activity”?
The activity is a measure of the nuclei that decay in 1 second.
What is the equation for activity?
A= N / t
What is the unit of activity?
Becquerels (Bq)
What does an unstable source emit?
Alpha, Beta, or Gamma
What is “half life”?
Half Life is the time it takes for the activity of a source to half.
A radioactive source has an activity of 100MBq. If it’s half life is 3 hours, calculate it’s activity 12 hours later.
6.25MBq
The activity of a radioactive source falls from 240MBq to 15MBq in a time of 24 hours. Calculate the half life of the source.
6 hours
After 8 hours the activity of a source has decreased to 20MBq. Calculate the initial activity of the source if it has a half life of 2 hours.
320MBq
What is “Dosimetry”?
This is the science of measuring the dosage of radioactivity.
What is “Absorbed Dose”?
This measures the radiation energy that is absorbed per kilogram of metal.
What is the formula for Absorbed Dose?
D = E / M
What is the formula “ A = N / t “ for?
Activity
What is the formula “ D = E / M “ for?
Absorbed Dose
What are the units for Absorbed Dose?
- Joules per Kilogram (Jkg^-1)
* Gray (Gy)
What is Absorbed Dose usually measured in?
- 1 uGy = (1x10^-6) Gy
* 1 mGy = (1x10^-3) Gy
What is 1 uGy equal to?
(1x10^-6) Gy
What is (1x10^-6) Gy equal to?
1 uGy
What is 1 mGy equal to?
(1x10^-3) Gy
What is (1x10^-3) Gy equal to?
1 mGy
50 uGy of radiation is absorbed by 500g of body tissue. Calculate the energy absorbed by the tissue.
50 uGy
What is “Equivalent Dose”?
Equivalent Dose is a better measure of the biological effect of radiation exposure.
What is the formula for Equivalent Dose?
H = D x WR
What is the formula “ H = D x WR “ used for?
Equivalent Dose
What is Equivalent Dose measured in?
Sievert (Sv)
What factors effect biological damage?
- Total absorbed dose
- Equivalent Dose
- Time Exposed
- Type of radiation
- Shielding
- Distance
- Absorbing tissue type
What is “nuclear fission”?
Nuclear fission is the splitting of a large nucleus. A neutron is fired at a Uranium atom, and the neutrons produced go on and on to create a chain reaction. This chain reaction releases a lot of energy.
What is “nuclear fusion”?
Nuclear fusion is the joining of 2 smaller nuclei. Nuclear fusion often occurs in stars.
What are the advantages of nuclear energy?
- Smaller mass of fuel required compared ti fossil fuels for same energy output
- No greenhouse gases
- Nuclear fuel will be a longer lasting supply compared to fossil fuels
What are the disadvantages of nuclear energy?
- Radioactive waste is produced
- Expensive to build and decommission nuclear power stations
- Potential for big accidents
