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The intensity of gamma- rays falls to 1/8th of its value after passing through 27 mm of lead toil. What should be thickness of the foil to reduce intensity of gamma- rays of its original value? |
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Answer» 24 mm Here, `mu="absorption coefficient of FOIL"` x=thickness of the foil First case : `I_(0)/8=I_(0) e^(-27mu)` `1/8=e^(-27mu)` or `(1/2)^(3)=(e^(-9mu)^(3)` `therefore 1/2 =e^(-9mu)` `or 1/2 I_(0)=I_(0) e^(-9mu) ............(2)` Comparing with equation (1) intensity is reduced to `1/2 I_(0)` when x=9mm |
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