The fraction of a radioactive material which reamins active after time t is 9//16 . The fraction which remains active after time t//2 will be .
20% radioactive sample decay in time t. How much sample decay in time 2t ?
Half-life of a certain radioactive materal against alpha -decay is 138 days. After what lapse of time the undecayed fraction of the material will be 6.25 % ?
The equations (dN)/(dt) = - lambda N and N = N_(0)e^(- lambda t) describes how the number N of undecayed atoms in a sample of radioactive material, which initially (at t = 0 ) contained N_(0) undecayed atoms, varies with time t. Which one of the following statements about lambda is correct ?
The half life of radioactive substance is T. Then the fraction of the substance that has decayed in time t is-
If T is the half-life of a radioactive material, then the fraction that would remain after a time (T)/(2) is
A fraction f_1 of a radioactive sample decays in one mean life, and a fraction f_2 decays in one half life. Then
The deacy time t for radioactive element proceeds to 4 half-lives. The total decay time (t) in terms of average life (T) is given by:
If 'f' denotes the ratio of the number of nuclei decayed (N_(d)) to the number of nuclei at t = 0 (N_(0)) then for a collection of radioactive nuclei, the rate of change of 'f' with respect to time is given as : [ lambda is the radioactive decay constant]
The graph shows the log of activity ( log R ) of a radioactive material as a function of time t in minutes The half -life (in minutes) for the decay is closest to
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