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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

Show that half life period of radioactive material varies inversely to decay constant λ.

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प्रश्न

Show that half life period of radioactive material varies inversely to decay constant λ.

व्युत्पत्ती
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उत्तर

From law of radioactive decay,

`"N" = "N"_0  "e"^{-lambda"t"}`

at t = `"T"_{1"/"2}, "N" = ("N"_0)/2`

∴ `("N"_0)/2 = "N"_0  "e"^{-lambda"T"_{1"/"2}}` 

∴ `1/2 = "e"^{-lambda"T"_{1"/"2}}`

∴ `"e"^{lambda"T"_{1"/"2}} = 2`

∴ `lambda"T"_{1"/"2} = log_"e"2 = 0.693`

∴ `"T"_{1"/"2} = 0.693/lambda`

⇒ `"T"_{1"/"2} ∝ 1/lambda`

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