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प्रश्न
Define the terms (i) half-life (T1/2) and (ii) average life (τ). Find out their relationships with the decay constant (λ).
उत्तर
Half-life
The half-life of a radioactive substance is defined as the average time for which the nuclei of the atoms of the radioactive substance exist.
`t = t_(1/2)`
`R =1/2R_0`
`∴ t_(1/2)=(1n2)/λ`
`=(0.693)/4`
Average life or mean-life (τ):
`tau``=(λN_0int_0^oo te^(-λ1)dt)/N_0`
= `λint_0^oo te^(-λ1)dt`
`tau=1/lambda`
`∴ T_(1/2)=(1n2)/λ = tau 1n2`
संबंधित प्रश्न
Consider the fission of `""_92^238"U"` by fast neutrons. In one fission event, no neutrons are emitted and the final end products, after the beta decay of the primary fragments, are `""_58^140"Ce"` and `""_44^99"Ru"`. Calculate Q for this fission process. The relevant atomic and particle masses are
`"m"(""_92^238"U")` = 238.05079 u
`"m"(""_58^140"Ce")` = 139.90543 u
`"m"(""_44^99"Ru")` = 98.90594 u
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| Mass(u) | |
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