Radiation

Question 1

Why do atoms emit radiation?

Answer 1

To become more stable.

Question 2

What are the three types of radiation that can be emitted?

Answer 2

1. Alpha
2. Beta
3. Gamma

Question 3

What is an Alpha particle?

Answer 3

2 protons and 2 neutrons/Helium nucleus

Question 4

What is a Beta particle?

Answer 4

A fast moving electron.

Question 5

What is Gamma radiation?

Answer 5

An electromagnetic wave.

Question 6

What is a Source?

Answer 6

A material that contains radioactive atoms.

Question 7

What is the term for when a source has emitted radiation?

Answer 7

Decaying.

Question 8

What is Ionisation?

Answer 8

Ionisation is the addition or removal of an electron to create an ion

Question 9

Which particle causes the most ionisation?

Answer 9

Alpha.

Question 10

Why is radiation dangerous to humans?

Answer 10

It can damage healthy cells by ionising the atoms which make up the cells.

Question 11

What is a group of damaged cells called?

Answer 11

A tumour.

Question 12

What are detectors of radiation?

Answer 12

Geiger-Muller tube
Photographic film
Spark counters

Question 13

What can absorb Alpha particles?

Answer 13

A thin sheet of paper.

Question 14

What can absorb Beta particles?

Answer 14

Aluminium.

Question 15

What can absorb Gamma radiation?

Answer 15

Thick lead or thick concrete.

Question 16

Which type of radiation is the most penetrating?

Answer 16

Gamma radiation.

Question 17

What is the definition of activity?

Answer 17

Activity is the number of nuclear disintegrations (decays) per second.

Question 18

What is activity measured in?

Answer 18

Becquerels (Bq)

Question 19

What is background radiation?

Answer 19

Background radiation is the radiation that is around us all the time.

Question 20

Why is background radiation counted?

Answer 20

When measuring the activity of an unshielded source it is important that the background count is measured. The background count must then be subtracted from all readings taken.

Question 21

What is the Half Life?

Answer 21

The time for the activity to half.

Question 22

What are the three factors that the biological effect of radiation depend on?

Answer 22

1. Absorbed dose
2. Type of radiation
3. Type of tissue absorbing the radiation.

Question 23

What is the symbol for absorbed dose and what is it measured in?

Answer 23

Symbol: D
Unit: Grays (Gy)

Question 24

What does the equivalent dose measure?

Answer 24

The equivalent dose is a measure of the biological harm that the radiation has on a tissue.

Question 25

What is the symbol of equivalent dose and what is it measured in?

Answer 25

Symbol: H Units: Sieverts (Sv)

Question 26

What are safety precautions when handling sources?

Answer 26

1. Limit the time of exposure 2. Use shielding e.g. store sources in a labelled lead lined container 3. Increase the distance between you and the source e.g. use tongs or forceps 4. Point sources away from the body (especially the eyes) 5. Wash hands after use

Question 27

How is radiation used in medicine?

Answer 27

1. As a tracer. A gamma source can be injected into your body and used as a radioactive tracer to study the flow of blood around the body. 2. To kill cancer cells. High energy gamma rays can be directed at the tumour, or an alpha source can be placed next to the tumour, to kill the cancerous cells. 3. To sterilise medical equipment. Radiation can be used to kill bacteria on medical equipment.

Question 28

What are other uses of Radiation?

Answer 28

1. To generate electricity in power stations. 2. In a smoke detector. Alpha radiation is used to detect if there are smoke particles in the room or not. 3. To sterilise food. Gamma radiation can be used to kill bacteria on the food and increase its shelf life. 4. To detect the thickness of paper and foil. Beta radiation can be used to ensure the paper or foil is the right thickness. 5. To detect flow rate of liquids in pipes.

Question 29

What are the two types of nuclear radiation?

Answer 29

Nuclear fusion and nuclear fission.

Question 30

What is nuclear fission?

Answer 30

In Nuclear Fission, a nucleus of large mass number is split into nuclei of smaller mass number with the release of energy and two or three neutrons.

Question 31

How can a chain be created in nuclear fission?

Answer 31

The neutrons that are produced can split further nuclei and cause a chain reaction.

Question 32

What is nuclear fusion?

Answer 32

In Nuclear Fusion nuclei of smaller mass number join/recombine to form a nucleus of larger mass number with the release of energy.

Question 33

What are some advantages of nuclear fission?

Answer 33

1. The fission process produces no greenhouse gases which are partly responsible for global warming. 2. The supply of electricity is very reliable. 3. A small amount of fuel creates a large amount of electricity.

Question 34

What are some disadvantages of nuclear fission?

Answer 34

1. The fission reaction produces nuclear waste which remains dangerous for hundreds of years. This is very dangerous. 2. Nuclear waste has to be stored safely for a long time. 3. Nuclear power stations are expensive to build and expensive to decommission once they have come to the end of their working lives.

Question 35

What are some advantages of nuclear fusion?

Answer 35

1. The fusion reaction is a very clean process. It does not produce greenhouse or radioactive waste. 2. The fuel is a type of hydrogen atom which is in plentiful in sea water.

Question 36

What is a disadvantage of nuclear fusion?

Answer 36

1. The fusion process requires temperatures similar to the core of the Sun to fuse the nuclei together. Creating temperatures this high is very difficult and expensive.

Question 37

What are some natural sources of radiation?

Answer 37

1. Cosmic rays - radiation that reaches the Earth from space 2. Radon gas - this radioactive gas is given off by tiny amounts of uranium that occurs in rocks and soil 3. Rocks and building materials - rock, stone and building materials like concrete, bricks and ceramics all emit radiation 4. Food and drink - plants absorb radioactive materials from the soil and these pass up the food chain 5. Water 6. Air