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A radioactive substance decays for an intervalof time equal to its mean life. Find the fraction of the amount of the substance which is left undecayed after this time interval. |
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Answer» Solution :We know that `N_(t)=N_(0)e^(-LAMBDA t)` and AVERAGE (mean) life `TAU= (1)/(lambda)`, hence amount of substance left undecayed after a TIME interval `tau` will be `N_(tau)=N_(0) e^(-lambda t)=N_(0).e^(-lambda((1)/(lambda)))=N_(0) e^(-1)=(N_(0))/(e )=0.368N_(0)` `rArr (N_(tau))/(N_(0))=(1)/(e )=0.368` |
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