P4 - Ionising Radiation

Question 1

What are some examples of ionising radiation?

Answer 1

X rays
Alpha
Beta
Gamma
These are all types of ionising radiation.

Question 2

How is ionisation caused?

Answer 2

• Some materials absorb ionising radiation, it can enter living cells and interact with molecules
• These interactions produced charged particles called ions
• This is ionisation.

Question 3

Why does ionisation occur?

Answer 3

Ionisation occurs because the particle gains or loses electrons.

Question 4

What kind of charge do atoms receive when interacting with X rays and Gamma rays & why?

Answer 4

• X-rays and gamma rays can transfer energy to electrons.

- The electrons then have enough energy to escape from the atom, ionising it and leaving it positively charged.

Question 5

What kind of charge do atoms receive when interacting with alpha particles & why?

Answer 5

• Beta particles can remove electrons from atoms or molecules they collide with, this leaves them positively charged.
• However a beta particle can also stick to an atom, ionising it and making it negatively charged.

Question 6

What happens when Alpha particles interact with atoms & molecules?

Answer 6

• Alpha particles can remove electrons from atoms and molecules they pass by or hit, making them positively charged.

Question 7

What are alpha particles good Ionizers?

Answer 7

• They are relatively large, so it is easy for them to collide with atoms or molecules
• They are highly charged, so they can easily remove electrons from the atoms they pass or collid ewith.

Question 8

What can low doses of ionising radiation cause?

Answer 8

• Low doses of ionising radiation tend to cause minor damage without killing the cell.
• This can give rise to mutant cells which divide uncontrollably which is cancer.

Question 9

What can higher dosages of ionising radiation cause?

Answer 9

Higher doses tend to kill cells completely which causes radiation sickness if a lot of cells all get blasted at once.

Question 10

What radiations are most dangerous outside the body?

Answer 10

Outside the body beta and gamma sources are the most dangerous.

Question 11

Why are beta and gamma sources the most dangerous outside the body?

Answer 11

• Beta and gamma can still get inside to the delicate organs, they can pass through the skin.

Question 12

Why is alpha much less dangerous than beta or gamma, when outside the body?

Answer 12

• Alpha is much less dangerous outside the body because it can’t penetrate the body.

Question 13

What is the most dangerous radiation when inside the body?

Answer 13

Alpha is the most dangerous when inside the body.

Question 14

Why is Alpha the most dangerous inside the body?

Answer 14

They can do all of their damage within a localised area, they also more ionising.

Question 15

Why are beta & gamma less dangerous inside the body?

Answer 15

• They are less ionising.

- They mostly pass straight out without doing much damage

Question 16

What type of waves are X rays and Gamma Rays?

Answer 16

X rays and Gamma Rays are high frequency, short wavelength electromagnetic waves.

Question 17

How are gamma rays made?

Answer 17

• Gamma rays are released from some unstable atomic nuclei when they decay.
• Nuclear decay is completely random, so there is no way to control when it is released.

Question 18

How are X rays made?

Answer 18

• X rays can be produced by firing high speed electrons at a heavy metal like tungsten, these are much easier to control than gamma rays.

Question 19

How do X rays respond to flesh & bone?

Answer 19

They can pass easily through flesh, but not so easily through thicker and denser materials like bones or metal.

Question 20

How are x ray images produced?

Answer 20

• The thicker or denser the material the more x ray that is absorbed, so it is the varying amount of radiation that is absorbed ( or not absorbed ) that make an x ray image.