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Worksheet: Ionizing Radiation


One half the ๐›พ -rays from a 99mTc sample are absorbed by a 0.170-mm-thick lead shielding layer. Half of the ๐›พ -rays that pass through the first layer of lead are absorbed in a second layer of equal thickness. What thickness of lead will absorb all but one in 1 0 0 0 of these ๐›พ -rays?


A 2.00-cm-thick sodium-iodide crystal absorbs all but 1 0 . 0 % of rays from a radioactive source. What percentage of rays will not be absorbed by 4.00-cm thickness of the same material?