Radiation P1

Question 1

What is an alpha particle?

Answer 1

A helium nucleus emitted by radioactive substances

Question 2

Describe the structure of an alpha particle

Answer 2

Consists of two protons and two neutrons, relative mass is 4 and charge is +2

Question 3

What can alpha particles be stopped by?

Answer 3

Paper

Question 4

What is a beta particle?

Answer 4

A fast moving electron emitted by radioactive decay

Question 5

Describe the structure of a beta particle

Answer 5

Consists of an electron emitted when a neutron in the nucleus turns into a proton, relative mass is 0 and charge is -1

Question 6

What material stops beta radiation?

Answer 6

Aluminium

Question 7

What is gamma radiation?

Answer 7

A high energy, high frequency wave

Question 8

What is gamma’s charge and mass?

Answer 8

No mass or charge

Question 9

What can gamma radiation be stopped by?

Answer 9

Lead

Question 10

What happens when an element emits an alpha particle?

Answer 10

It loses two neutrons and two protons so the atomic mass decreases by 4 and the atomic number decreases by 2

Question 11

What happens when an element emits a beta particle?

Answer 11

The atomic mass is unchanged but the atomic number increases by 1 because a neutron turns into an electron and proton

Question 12

What happens to an element when it emits gamma radiation?

Answer 12

Does not alter mass or proton number

Question 13

Define ionising power

Answer 13

How easily different types of radiations can cause other atoms to lose electrons and form ions

Question 14

Which type of radiation is the most ionising and why?

Answer 14

Alpha because it has the highest charge so highly ionises atoms easily as it passes them

Question 15

Which is the least ionising and why?

Answer 15

Gamma as it is a wave without charge which does not interact with atoms when it touches them

Question 16

Why would an older source of cobalt be less radioactive than a new one?

Answer 16

It’s had time to decay

Question 17

Why can’t we predict when a particular atom will decay?

Answer 17

It is a random process however we know a fixed amount will decay each time

Question 18

What is the half life of an isotope?

Answer 18

The average time it will take for half of the nuclei present to decay. If the half life of a sample was 30 years, half of its nucleus would decay in the first 30 years then in the next 30 years a quarter of the original sample would decay (half of the new amount (half of one half)) then after another 30 years one eighth of the original sample would decay (half of the new amount (half of quarter))

Question 19

Why can gamma radiation penetrate further?

Answer 19

It has no charge or mass but this means they are weakly ionising as they tend to pass through rather than collide with atoms

Question 20

Why is radiation dangerous?

Answer 20

Can enter living cells which can mutate incorrectly and become cancerous or they can be killed off completely

Question 21

Name 2 natural sources of background radiation

Answer 21

Radon, cosmic rays

Question 22

Name 2 artificial sources of background radiation

Answer 22

X rays, nuclear power

Question 23

Define ionising radiation

Answer 23

Different types of radiations cause other atoms to lose electrons and form ions

Question 24

What is a use of alpha particles in the home?

Answer 24

Used in smoke detectors by ionising air particles causing a current to flow. If there is smoke in the air is binds to the ions meaning the current stops and the alarm sounds

Question 25

What is a use of beta radiation?

Answer 25

Beta emitters are used to test the thickness of sheets of metal because they are moderately ionising so the particles are not immediately absorbed by the material like alpha radiation would be and do not penetrate as far as gamma rays. Therefore slight variations in thickness affect the amount of radiation passing through the sheet

Question 26

How can radiation be measured?

Answer 26

With a Geiger-Muller tube and counter which records the count rate (number of radiation counts reaching it per second)

Question 27

What can half life be used for?

Answer 27

To find the rate at which a source decays -its ACTIVITY which is measured in becquerels, Bq where 1Bq is 1 decay per second

Question 28

What is the problem with trying to measure how long it takes for nearly all unstable nuclei to decay?

Answer 28

Activity never reaches zero

Question 29

What does it mean to irradiate something?

Answer 29

Be exposed to a radioactive source

Question 30

Identify 3 ways of reducing irradiation

Answer 30

Keeping sources in lead lined boxes, standing behind barriers or being in a different room and using remote controlled arms when working with radioactive sources

Question 31

Define contamination

Answer 31

Unwanted radioactive atoms getting onto or into an object , these contaminating atoms may then decay to release radiation which would cause you harm as radioactive particles could get inside your body

Question 32

How can you avoid radioactive particles getting stuck to your skin and under your nails or getting breathed in?

Answer 32

Use gloves and tongs when handling them, wear protective suits to stop you breathing the particles in

Question 33

Why is irradiation from beta and gamma sources more dangerous than from alpha?

Answer 33

Outside the body beta and gamma can penetrate the body and get to delicate organs whereas alpha is easily blocked by small air gaps and cannot penetrate the skin

Question 34

Why is contamination from alpha the most dangerous?

Answer 34

Inside the body alpha do all their damage in a very localised area whereas with beta sources radiation is absorbed over a wider area and some passes out of the body altogether and gamma mostly pass out straight away