Dangers of radiation

Question 1

What type of radiation is dangerous?

Answer 1

ionising radiation

e.g.

• x-rays
• protons
• neutrons
• alpha beta and gamma radiation

Question 2

Why is ionising radiation dangerous?

Answer 2

• it can destroy cell membrane which causes cells to die, or
• it can damage vital molecules
  
  • such as DNA directly
  • or indirectly by creating free radical ions which react with vital molecules
  • normal cell division is affected and nuclei become damaged
  • causes a tumour - cells divide and grow uncontrolably
  • damaged DNA is sex cells may cause a mutation which can be passed on to future generation

Question 3

WHat are the two general effects of radiation?

Answer 3

• somatic effects
  
  • affects the health of the affected person
• genetic effects
  
  • possible affecting future generations

Question 4

How is radiation monitored?

Answer 4

• anyone using equipment that produces ionising radiation must wear a film bade to monitor their exposure to ionising radiation

Question 5

How does the film badge work?

Answer 5

• contrains a strip of photographic film in a light-proof wrapper
• different areas of the film are convered by absorbers of different materials and different thicknesses
• when the film is developed the amount of exposure to each from of ionising radiation can be estimated from the blackening of the film
• if the bade is overexposed, the wearer is not allowed to continue working with the equipment

Question 6

What is the dose measured in?>

Answer 6

terms of energy absorbed per unit of matter from the radiation

Question 7

How do radiation sources differ?

Answer 7

• same dose of different types of ionising radiation has different effects
• e.g. alpha radiation produces far more ions per millimetre than gamma radiation in the same substance so it is more damage
• however alpha radiation from a source outside the body cannot penetrate the skin’s outer layer of dead cells so is much less damaging than if the source were inside the body

Question 8

• A friend who has not studied physics suggests that a smoke detector containing radioactive material should not be sold.
• • Use your knowledge of physics to explain why a smoke detector containing americium-241 does not provide any risk to the user.

Answer 8

• Only a small quantity of material is needed
• The particles it emits do not travel more than a few centimetres