National 5 Physics | Radiation | Half-life | WORKED EXAMPLES
T1/2=ln(2)λ≈0.693λcap T sub 1 / 2 end-sub equals the fraction with numerator l n 2 and denominator lambda end-fraction is approximately equal to the fraction with numerator 0.693 and denominator lambda end-fraction For general calculations of the remaining mass ( Ntcap N sub t ) after a certain time (
: Half-life is constant for a specific isotope and cannot be changed by physical or chemical means. Half-Life-Alyx-TRNT.rar
Nt=N0(12)tT1/2cap N sub t equals cap N sub 0 open paren one-half close paren raised to the the fraction with numerator t and denominator cap T sub 1 / 2 end-sub end-fraction power Determining Half-Life from a Graph
A common method for finding half-life is using a decay curve (activity vs. time). : Locate the starting point ( N0cap N sub 0 ) on the vertical axis (y-axis). Calculate Half-Value : Divide the initial activity by 2 ( National 5 Physics | Radiation | Half-life |
: Activity is measured in Becquerels (Bq) , representing one decay per second. The Mathematical Formula The relationship between the decay constant ( ) and the half-life is defined by the following equation:
: You cannot predict when a single nucleus will decay, but you can predict the behavior of a large sample. : Locate the starting point ( N0cap N
) of a radioactive isotope is the time required for half of the unstable nuclei in a sample to undergo radioactive decay. :