Radiation

Question 1

DESCRIBE THE MODEL OF AN ATOM

Answer 1

• In an uncharged atom, the number of protons in the nucleus are even to the number of electrons orbiting the nucleus.
• The nucleus contains protons and neutrons.
• Electrons, negative.
  Protons, positive
  Neutrons, neutral

Question 2

DESCRIBE ALPHA RADIATION

Answer 2

An alpha particle is a helium nucleus (two protons and two neutrons) with a positive charge. It is large in size compared to beta.

Question 3

DESCRIBE BETA RADIATION

Answer 3

A beta particle is a high speed electron (produces within the nucleus) and is negative. It is small compared to alpha.

Question 4

DESCRIBE GAMMA RADIATION

Answer 4

Gamma radiation is a high frequency, high energy electromagnetic wave. It travels at the speed of light.

Question 5

HOW DOES A RADIOACTIVE MATERIAL BECOME STABLE

Answer 5

A radioactive material is made up of atoms with unstable nuclei. They become stable when the nucleus decays and emits alpha, beta or gamma.

Question 6

DESCRIBE IONISATION

Answer 6

Ionisation is when an electron is added to an atom or lost from an atom making it charged. What is left is called an ion. Alpha is most ionising and gamma is least ionising.

Question 7

HOW DOES RADIATION KILL LIVING CELLS

Answer 7

When living tissue receives a dose of radiation, ionisation takes place which can disrupt the way the cells operate.

Question 8

HOW DOES A GEIGER MULLER TUBE WORK

Answer 8

The tube detects gas. The ions in the gas produce a current in the tube for a short time. This current produces voltage pulses and the voltage pulses are measured on the counter.

Question 9

WHAT IS EACH RADIATION ABSORBED BY

Answer 9

• Alpha radiation is absorbed by a piece of paper or a few cm of air
• Beta is absorbed by a few mm of aluminium or a few m of air.
• Gamma is absorbed by a few cm of lead or a few km of air.

Question 10

WHAT IS ACTIVITY

Answer 10

The number of radioactive decays per second (Bequerells)

Question 11

WHAT IS BACKGROUND RADIATION

Answer 11

Background radiation is radiation from our surroundings and is normally at a low level.

Question 12

WHAT ARE NATURAL SOURCES OF RADIATION

Answer 12

Radon gas from rocks, Gamma rays from the ground, Cosmic rays from space.

Question 13

WHAT ARE ARTIFICIAL SOURCES OF RADIATION

Answer 13

Medical applications such as tracers, fallout from weapon testing, nuclear waste from power stations.

Question 14

MEDICAL APPLICATIONS OF RADIATION

Answer 14

Radiotherapy, x-rays, tracers

Question 15

INDUSTRIAL APPLICATIONS

Answer 15

Testing welds

Question 16

WHAT JOBS ARE EXPOSED TO RADIATION EACH YEAR

Answer 16

Miners, nuclear power plant workers and aircrew are exposed to large doses of radiation each year

Question 17

WHAT IS ABSORBED DOSE

Answer 17

The absorbed dose is the energy absorbed per unit mass of the absorbing material (Grays)

Question 18

WHAT IS THE EQUIVALENT DOSE

Answer 18

The equivalent dose is the measure of biological harm caused by the radiation

Question 19

WHAT IS THE RADIATION WEIGHTING FACTOR

Answer 19

The measure of biological effect of a radiation

Question 20

WHAT IS THE EQUIVALENT DOSE RATE

Answer 20

The equivalent dose per unit time

Question 21

THREE RANDOM PIECES OF INFORMATION

Answer 21

1. Average annual background radiation in the UK is 2.2mSv.
2. Annual effective dose limit for members of the public is 1mSv.
3. Annual effective dose limit for a radiation worker is 20mSv.

Question 22

WHAT ARE THREE WAYS TO PROTECT YOURSELF FROM RADIATION

Answer 22

Shielding, limit time of exposure, distance from source

Question 23

WHAT ARE APPLICATIONS OF ALL THREE TYPES OF RADIATION

Answer 23

Gamma rays - radio therapy.
Beta - measuring the thickness of materials.
Alpha - smoke detectors.

Question 24

WHAT IS THE HALF LIFE OF A SOURCE

Answer 24

The half life is the time taken for a radioactive sources activity to drop to half its previous value. (The activity of any radioactive source decreases with time).

Question 25

WHAT IS THE HALF LIFE EXPERIMENT

Answer 25

1. Use a stop clock and counter to measure the amount of counts in one minute. 2. Repeat this ten minutes later. 3. Repeat every ten minutes for two hours. 4. Measure the background radiation and deduct it from the values. 5. Plot the results on a graph and measure the half life.

Question 26

WHAT IS FISSION ( SPONTANEOUS AND INDUCED)

Answer 26

Fission is when a heavy nuclear disintegrates leaving two nuclei of smaller mass and some neutrons. Spontaneous fission - Nucleus is unstable. Induced fission - reaction is started when a fast moving neutron collided with a Uranium nucleus, making is unstable (nuclear power stations).

Question 27

WHATS A CHAIN REACTION (UNCONTROLLED FISSION REACTION)

Answer 27

When the neutrons released go on to create other fission reactions. If a reaction isn’t kept under control, it can make a bomb

Question 28

BENEFIT AND PROBLEM OF USING FISSION TO PRODUCE ENERGY

Answer 28

Nuclear power stations can produce large amounts of energy with small amounts of fuel using nuclear fuel but nuclear waste must be stored securely for a long time.

Question 29

WHAT IS FUSION AND WHERE DOES IT TAKE PLACE

Answer 29

when two or more nuclei combine to form an element with a higher mass number. Fusion takes place in the sun and stars.

Question 30

PLASMA CONTAINMENTS (PROBLEMS WITH FUSION TO GENERATE ENERGY)

Answer 30

For fusion to take place, atoms must be heated to temperatures around 40 000 000 Kelvin to be pressurised enough for fusion to occur. When atoms are heated to such heats, they become a different state of matter called plasma. Containing plasma can only be done with strong magnetic field and is very difficult and expensive.

Question 31

WHAT DOES THE BIOLOGICAL EFFECTS OF RADIATION DEPEND ON

Answer 31

The risk of biological harm from radiation depends on the type of radiation, the type of tissue, the absorbed dose.

Question 32

WHAT ARE THE ENVIRONMENTAL HAZARDS OF RADIATION

Answer 32

High doses of radiation can be fatal to plants, humans and animals. Low doses can cause sickness and mutations.

Question 33

6 SAFETY PROCEDURES

Answer 33

1. Always use forceps to handle a source, never bare hands. 2. Always arrange the source so that its radiation window faces away from the body. 3. Never bring a radioactive source close to your eyes to identify, always identify by a colour or number. 4. A source must always be attended to by an authorised person and must be returned to a lead lined box. 5. Always wash your hands after any experiment with a radioactive material. 6. The warning sign must always be displayed whenever radioactive sources are stored.

Question 34

WHAT IS THE RADIATION WARNING SIGN

Answer 34

three way gas sign in a triangle