• Question: My teacher says that, when a chemical reaction takes place, all of the atoms have to go somewhere. The same amount of atoms come out (in whatever products they have formed in the process) as go in. Does radiation work like this? (e.g. if you have your arm x-rayed, will the radiation come out as a different type of radiation, or does it simply disappear?)

    Asked by danniegee to Philip, Ceri, Arttu on 16 Jun 2011.
    • Photo: Arttu Rajantie

      Arttu Rajantie answered on 16 Jun 2011:

      Radiation does not work like that. Radiation is made of photons, and the number of photons is not conserved, unlike the number of atoms. Energy is conserved, so the energy of the radiation has to go somewhere, and it mainly ends up as heat.

    • Photo: Ceri Brenner

      Ceri Brenner answered on 16 Jun 2011:

      Arttu’s right, the principle that governs here is that energy is always conserved-it cannot be created or destroyed, but can be transformed from one form to another (oh my gosh, i literally think i have just recited that from my GCSE, it’s ingrained in my memory ha, but has proven to be quite useful). radiation is made up of energetic particles or photons (x-rays in your example) which tend to transform their energy into heat when they come into contact with matter.

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