Radioactivity

Question 1

What are the 3 different types of ionising radiation?

Answer 1

Alpha
Beta
Gamma

Question 2

What are the properties of alpha radiation?

Answer 2

-contains 2 protons and 2 neutrons
-it is the largest
-it is the slowest
-its charge is +2e
-it is absorbed by paper,skin,a few cm of air
-harmful inside body

Question 3

What are the properties of beta radiation?

Answer 3

-contains a single electron
-small
-close to speed of light
-change= -1e
-absorbed by light metals, a few mm of aluminium and a few m of air
-can harm inside body and can pass into body from outside the skin

Question 4

What are the properties of gamma radiation?

Answer 4

-no size
-fastest (speed of light)
-no charge
-absorbed by a thick sheet of lead, meters of concrete and 1000s of kms of air
-harmful both inside and outside of body

Question 5

What do geiger counters do?

Answer 5

They detect radioactivity and turn it into a current which can be displayed as a value or a sound (click).

Question 6

What is the activity of a radioactive source?

Answer 6

The number of radioactive nuclei decaying per second

Question 7

What is activity measured in?

Answer 7

Becquerels (Bq)

Question 8

Radioactive decay decreases exponentially. Explain.

Answer 8

-it decreases rapidly at first and then slows down as there are fewer stable nuclei left to decay
-the sources decays at a fixed rate which can be measured by using its ‘half life’

Question 9

What is half life?

Answer 9

The time taken for activity of a radioactive source to fall by half

Question 10

What is carbon 14?

Answer 10

It is an isotope of carbon that is radioactive. It decays through beta decay to form nitrogen.

Question 11

What is contamination?

Answer 11

The source is inside your body or on your skin or clothing

Question 12

What is iradiation?

Answer 12

You are exposed to radiation from and external source outside your body and clothes

Question 13

What is ionising radiation?

Answer 13

Radiation with enough energy to change the electron structure of an atom

Question 14

How can radiation affect a person?

Answer 14

-radiation enters body
-radiation ionised atoms in cells DNA
-these mutations could become cancerous cells

Question 15

safety precautions to take when using radioactive sources:

Answer 15

-reduce your time of exposure
-handle with tools or tongs
-wear protective clothing
-point source away from body
-contain sources behind thick lead
-when Finnished, use a geiger counter to see how much radiation you have been exposed to

Question 16

Uses of alpha radiation?

Answer 16

Smoke alarms
Powering small devices
Fuel sources for satellites
Old pacemakers

Question 17

Uses of beta radiation

Answer 17

-testing thickness of thin sheet material
-medical tracers to look inside the body
-particle physics

Question 18

Uses for gamma radiation

Answer 18

-sterilising medical equipment
-sterilising food
-radiotherapy

Question 19

What are the advantages of nuclear power?

Answer 19

-very efficient
-does not produce greenhouse gases
-very reliable
-not much waste produced
-uranium about the same price as coal

Question 20

Disadvantages of nuclear power?

Answer 20

-waste is radioactive and potentially dangerous for a very long time and difficult to store
-power station accidents can be catastrophic
-power stations are expensive to build and decommission due to safety measures

Question 21

What is nuclear fission?

Answer 21

It is the splitting of an atom which releases energy. It can be spontaneous but in a nuclear reactor it is made to happen.

Question 22

How does nuclear fission happen?

Answer 22

Nuclear fission is the chain reaction when massive, neutron rich Nuclei are split when a slow moving neutron collides with them. This splitting causes vast amounts of energy, the nucleus splits into two daughter nuclei as well as releasing more neutrons to create a self sustaining chain reaction.

Question 23

What is a common nuclear fuel and why?

Answer 23

Uranium because it’s nucleus is very large and unstable

Question 24

Nuclear fusion is the opposite of nuclear fission. True or false

Answer 24

True

Question 25

What is nuclear fusion?

Answer 25

Where two light nuclei collide at high speed and fuse to create a larger heavier one.

Question 26

Which releases more energy fusion or fission?

Answer 26

Fusion

Question 27

Why haven’t scientists found a way to use fusion to generate energy for us to use?

Answer 27

The temperatures and pressures needed for fusion are so high that fusion reactions are expensive and really hard to build.

Question 28

Where does fusion happen?

Answer 28

During the main sequence of their lives, stars like our sun are powered by nuclear fusion of hydrogen and helium.