Radiation
Radiation is energy on the move, and it comes in two kinds: particles leaving a nucleus, and light of high energy. What makes it dangerous is being ionising, that is, carrying enough energy to tear electrons off the atoms it passes; if the atom it breaks sat in a DNA molecule, it breaks that too. Alpha is helium nuclei and does not get past paper; beta is electrons and aluminium stops it; gamma is light and needs lead. The less one penetrates, the more damage it does where it lands.
Where this sits
- Comes after
- Waves
- Opens up
- The spectrum, The nucleus
Exercises from this rung
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What does it mean for radiation to be ionising?
- That it tears electrons off atoms
- That it goes through metals
- That it heats what it touches
- That it glows in the dark
Why It carries enough energy to tear electrons off the atoms it passes through. That is what makes it dangerous: if the atom it breaks sits in a DNA molecule, it breaks that too. Visible light and radio waves never reach that energy, which is why they do not ionise however much there is.
easierWhat is radiation used for in “seeing a broken bone”?
- It is a use of radiation
- It only uses sound
- It does not use radiation
- It only uses magnets
Why All three are. Ionising radiation kills bacteria, passes through flesh but not bone, and the carbon-14 we all carry decays at a known rate that works as a clock. It is the same physics that makes a nuclear leak dangerous: what changes is the dose, not the nature.
in betweenPut them in order from least to most penetrating.
Answer alpha, beta, gamma
Why Alpha, beta, gamma. It is the order of size backwards: alpha is whole helium nuclei and they bump into everything at once; beta is electrons, far smaller; gamma has no mass at all, it is pure light of enormous energy, and it goes where nothing else does.
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