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A count rate meter is used to measure the activity of a given sample. At one instant meter shows 2400 counts/min. One hour later the count drops to 300 counts per minute. What is half life of the sample ? |
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Answer» 5 mintues `N/N_(0)=A/A_(0)=(1/2)^(t/T)," A=300/min and"` `A_(0)="2400/min"` `(300)/(2400)=(1/2)^(t/T) rArr 1/8=(1/2)^(t/T)` `rArr (1/2)^(3)=(1/2)^(t/T)` This gives `t/T=3 or T =t/3 =(1HR)/(3)=20"min"` |
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