7 - Radiation

Question 1

What can unstable nuclei emit?

Answer 1

Radiation to become more stable

Question 2

How do unstable nuclei decay?

Answer 2

By emitting high energy particles or waves

Question 3

Why type of process is radioactive decay?

Answer 3

Random

Question 4

What charge do alpha particles have?

Answer 4

+2

Question 5

What can alpha particles be affected by?

Answer 5

An electric field

Question 6

When are beta particles produced in nuclei?

Answer 6

When a neutron changes into a proton and an electron

Question 7

What charge do beta particles have ?

Answer 7

-1

Question 8

Which type of electromagnetic wave has the highest energy?

Answer 8

Gamma rays

Question 9

What is the charge on gamma rays ?

Answer 9

No charge

Question 10

What is alpha stopped by?

Answer 10

Paper

Question 11

What is beta stopped by?

Answer 11

A few millimetres of aluminium

Question 12

What can gamma rays be partially stopped by?

Answer 12

Thick lead

Question 13

What can gamma pass through?

Answer 13

Paper + aluminium

Question 14

What does ionising do to an atom?

Answer 14

Gives it a non-zero charge

Question 15

What is the most ionising form of radiation?

Answer 15

Alpha

Question 16

What is the least ionising form of radiation?

Answer 16

Gamma

Question 17

What happens when a nucleus emits a neutron ?

Answer 17

• total number of particles in nucleus decreases by 1

- the mass number decreases by 1

Question 18

What can radiation be measured and detected by?

Answer 18

A Geiger-Muller tube

Question 19

What is activity ?

Answer 19

The rate at which the unstable nuclei from a source of radiation decays

Question 20

What happens to the activity of a source with time?

Answer 20

It decreases

Question 21

What is half life?

Answer 21

The time taken for the activity of a sample to fall to half its original level

Question 22

Gives examples of uses of radioactivity?

Answer 22

• smoke detectors
• sterilising medical equipment
• cancer treatment

Question 23

What can beta particles be used for?

Answer 23

To measure the thickness of thin materials eg paper, cardboard

Question 24

What can gamma particles be used for?

Answer 24

Radiotherapy + sterilising food

Question 25

When does contamination occur?

Answer 25

When a radioactive isotope gets onto a material where it should not be

Question 26

What is irradiation ?

Answer 26

The process of exposing a material to alpha, beta or gamma radiation

Question 27

What does contamination cause the material to become?

Answer 27

Radioactive

Question 28

What does irradiation cause the material to become?

Answer 28

NOT radioactive, however can kill living cells

Question 29

How can you protect against radiation?

Answer 29

- protective clothing | - shielded container

Question 30

What is fusion?

Answer 30

When 2 small nuclei join together to produce a larger nucleus

Question 31

What is fission?

Answer 31

One large nucleus splits into 2 smaller nuclei

Question 32

What is nuclear fission?

Answer 32

The splitting of a large unstable nucleus into 2 smaller nuclei

Question 33

Which isotopes undergo fission and are used in nuclear power stations?

Answer 33

Uranium + plutonium

Question 34

What is spontaneous fission?

Answer 34

When a nuclei undergoes fission without additional energy being put into the nucleus

Question 35

How does fission normally occur?

Answer 35

The unstable nucleus must first absorb a neutron

Question 36

What happens during the induced fission of uranium-235?

Answer 36

A neutron is absorbed by the uranium-235 nucleus to make uranium-236

Question 37

What are the products of fission?

Answer 37

- gamma rays - 2 daughter nuclei - 2 or 3 neutrons

Question 38

Describe a chain reaction

Answer 38

when a neutron splits a nucleus, releasing more neutrons, which go on to split even more nuclei

Question 39

What are control rods used for + made of ?

Answer 39

Boron- To absorb neutrons

Question 40

What does lowering the control rods do?

Answer 40

Decreases rate of fission - more neutrons absorbed

Question 41

What does raising the control rods do?

Answer 41

Increases rate of fission - fewer neutrons absorbed

Question 42

What is a moderator made of + used for ?

Answer 42

Graphite - To slow down neutrons

Question 43

What is the nuclear reactor surrounded with?

Answer 43

Shielding materials

Question 44

What is the purpose of shielding ?

Answer 44

To absorb hazardous radiation

Question 45

What keeps a nuclear reactor running ?

Answer 45

A chain reaction

Question 46

What 2 factors must be controlled when a rector is producing energy at the correct rate?

Answer 46

- number of free neutrons in reactor | - energy of the free neutrons

Question 47

What is nuclear fusion?

Answer 47

When 2 light nuclei join to form a heavier nucleus

Question 48

What are the conditions for fusion?

Answer 48

- very high temperature of fuel - very high kinetic energy - very high density/pressure

Question 49

Why can fusion not take place at a low temperature/low pressure

Answer 49

Positively charged nuclei need to be close to fuse, therefore need to be moving very fast to overcome the strong force due to electrostatic repulsion.