JAMB - Physics (2009 - No. 32)
A piece of radioactive material contains 10\(^{20}\) atoms.
If the half life of the material is 20 seconds, the number of disintegration in the first second is?
If the half life of the material is 20 seconds, the number of disintegration in the first second is?
3.47 x 1018
6.93 x 10 20
3.47 x 1020
6.93 x 1018
Explanation
The number of disintegration,∆N in time interval At, is given by
- ∆N = N∆t
Where N is the number of atoms present at the time t
But ^ = (0.693)/T
= 0.693 ÷ 20
= 0.0347
∴ ∆N = 0.0347 \(\times\) 10\(^20\)
= 3.47 \(\times\) 10\(^18\)
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