Chapter 7 📊 Flashcards
Which of the following are non ionising radiation? Beta Ultrasound Infrared Light Gamma rays X-rays
Light
Ultrasound
Infrared
What is someone who works with x rays called?
Radiographer
What radiation is used in an endoscope?
Light
How does light travel through an endoscope?
Total internal reflection
What radiation do CAT scans use?
Xrays
Ionising radiation is used to…
Treat cancer
Uses of ultrasound
Scan babies
Detect lumps
Break up kidney stones
What is released when fission takes place?
2 or 3 neutrons and energy
What radiation is produced when nuclear fission takes place?
Gamma radiation
What are the two smaller nuclei formed when fission occurs called?
Fission fragments
What are the most common substances used in fission reactors?
Uranium-235 and plutonium-239
What is gamma radiation?
High energy electromagnetic radiation
What is the charge of gamma radiation?
0
Mass of gamma radiation
0
Ionising power of gamma radiation
Very weakly ionising
What does it take to stop gamma rays?
A few centimetres of lead or several metres of concrete
What is a beta particle?
A high energy electron
Charge of beta particle
-1
Mass of a beta particle
Very small (1/1860)
Ionising power of beta particle?
Weakly ionising
How to stop beta radiation?
Few mm of aluminium
What is an alpha particle?
2 neutrons and 2 protons
Charge of alpha particle?
+2
Mass of an alpha particle?
4
Ionising power of alpha particle?
Strongly ionising
How to stop alpha radiation?
Few cm of air
Why do substances emit radiation?
The unstable nuclei become stable by doing so
What did Ernest Rutherford discover?
Alpha and beta radiation is made from different types of particles
What is the atomic number?
Number of protons or electrons
What is the mass number?
Mass of nucleus
Mass of a proton
1
Mass of a neutron
1
Mass of an electron
Very small (1/2000)
What is an alpha particle the same as?
A helium nucleus
What happens when a nucleus emits alpha particle?
Atomic number -2
Mass number -4
What happens when a nucleus emits a beta particle?
Atomic number +1
Mass number unchanged
What is ionisation?
When an atom loses electrons because it has been exposed to radiation
What is the activity of a radioactive source?
The number of unstable atoms in that source per second
What is the half life?
The time taken for the number of atoms to halve
Which type of radiation is used to destroy cancer cells?
Gamma
Which radiation is used in smoke alarms?
Alpha
Which radiation is used to measure thickness of foil?
Beta
What happens in fission?
The nucleus of a substance is struck by a neutron, causing the nucleus to halve and release neutrons
Example of a chain reaction
Nuclear fission
What is used in fission reactors?
Plutonium-239 and uranium-235
Why is there water in a reactor?
So the neutrons collide with the water atoms and slow down
What do control rods do?
Absorb neutrons to keep chain reaction under control
What is nuclear fusion?
When two smaller nuclei form one larger one
What is radon gas?
An isotope that emits alpha particles
Why is nuclear waste a problem?
Stays in environment for long time
What did Ernest Rutherford discover?
The nucleus
What makes a substance radioactive
An unstable nucleus
What is important to remember about radioactive decay
It is random and unpredictable
What was the plum pudding model of the atom
A cloud of positive charge with negative electrons sprinkled around
What did Rutherford use alpha particles for
Probe inside atoms
What happens when a substance is irradiated
It has been exposed to ionising radiation
What is radioactive contamination
The unwanted presence of materials containing radioactive atoms on other materials
What is the count rate of a sample
The number of counts per second
How are gamma rays used as tracers?
Person swallows some of the radioactive substance containing gamma rays
If the kidney is clear, the count should go up and down as water flows out of the kidney
If the kidney is blocked it stays high as the body can’t get rid of it
Why is iodine used as a tracer
It has a short half life
Why is gamma radiation used to treat cancer
It can penetrate further into the body
Why can fusion only take place when the nuclei are moving fast
They must overcome the electrostatic forces of repulsion
Why is fusion not currently being used for energy
It needs such high temperatures and pressures
