We know that the alpha, beta and gamma rays do penetrate through matter and all three have different penetrating abilities. What does it actually mean when it is said that a radiation of a particular particle is penetrating through matter? Does it mean that the particle moves through the matter undisturbed in its path?


1 Answer 1



For example, think of an $\alpha$ particle, which is just a Helium nucleus.

Its size is on the order of $10^{-15}$ meters, and the distance between atoms in a solid is on the order of $10^{-10}$ meters, meaning there is plenty of room for the particle to move in and penetrate matter.

  • $\begingroup$ what about radiation? and how lead sheet absorbs X-ray radiation? $\endgroup$
    – Mitchell
    Mar 18, 2017 at 13:31
  • 2
    $\begingroup$ @BhavyaSharma it's the same with radiation, there's a chance that the photon will interact with an atom on the way through and be absorbed. Think of throwing a rock in the forest; the space between trees is much larger than the rock, but throw the rock far enough and you're still likely to hit a tree because there are so many of them. $\endgroup$
    – Asher
    Mar 18, 2017 at 14:10

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