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Grade 12Modern Physics

The mean lives of radio active substances are 1620 years and 405 years for a particle and b particle respectively. Find out the time during three fourth of a sample will decay if it is decaying by both a and b emission simultaneously.

Profile image of Abhinandan
9 Years agoGrade 12
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1 Answer

Profile image of Vikas TU
9 Years ago
Total decal constant that is,
k = k1k2/(k1+k2) =>after putting the values k1 = 1620 and 405
net k = 1/324 year.
N/4 would left after disintegrating three-fourth and hence,
N/4 = e^-(kt)
taking log both sides we get,
t = (2/k)ln(2) = > 449 years. approx.