Radiation is transfer of energy through space via electromagnetic waves. Don’t worry, that’s not as scary as it sounds. It doesn’t require any medium to transfer it. It is the heat you’re feeling when you sit close to a fire or hold your hand above a preheated pan. The sun’s energy travels to the earth through the vacuum of space. Without radiation, our planet (and indeed, the universe) would be in a lot of trouble! An important fact to remember about radiant energy is that it decays (that is, gets weaker) by the inverse square law—the energy that reaches an object from a radiant energy source
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