Standard Grade Physics
From this lesson and for the exam, you should be able to:
State that radiation can kill living cells or change the nature of living cells.
State that radiation energy may be absorbed in the medium through which it passes.
State that the dose equivalent is measured in sieverts.
State that for living materials, the biological effect of radiation depends on the absorbing tissue and the nature of the radiation. Understand that the dose equivalent measured in sieverts takes account of the type and energy of radiation.
What types of radiation are harmful?
Why is ionising radiation harmful?
Radiation may be absorbed by the medium it passes through.
All living things contain living cells. We have many different types of cells which perform different functions including:
Red blood cells (they transport oxygen around the body)
White blood cells (they fight infection).
Radiation can kill living cells or change the nature of living cells.
Ionising radiation can kill or change the nature of living cells.
The effects of the damage inflicted by the ionising radiation may:
be severe and cause immediate effects, or
not become apparent for a long time.
The biological effect of radiation depends on:
The type of radiation.
The type of body tissue or body organ that absorbs the radiation.
The total amount of energy absorbed.
The Effects of Ionising Radiation
Short-term effects usually occur when there’s a large amount of exposure to radiation.
Short-Term Effects of Radiation
During the Second World War, two atomic bombs were dropped on Hiroshima and Nagasaki in Japan.
Those people who survived the blast were exposed to a large dose of radiation. Such doses caused severe damage to cells all over the body, especially in the skin, blood, bone tissue and gut.
Many of these people died within a few weeks. Those people who were exposed to a smaller dose recovered from such immediate effects.