How do I find the half-life of radioactive isotope?
The half-life of a radioactive isotope is the time taken for half of the atoms in a given sample of the isotope to decay. Radioactivity is random and so, half-life is the average time taken for a large number of atoms.
There are two ways to find the half-life, both come from the decay equation: N = N0e^(-λt) which is an exponential relationship*.
Where N is the number of atoms of the isotope left at time t and N0 is the number of atoms when t =0. λ is known as the decay constant and is the probability that an atom will decay per unit time. If you are given the decay constant you may find the half-life T1/2 by setting N = N0/2 and rearranging to find t = T1/2. Or if you are given N and N0 you may find λ and follow the previous steps.
*Make sure you familiar with exponentials and logs before attempting this topic
Related Physics A Level answers
All answers ▸In the Rutherford alpha scattering experiment, most particles passed straight through the foil with little or no deflection. What can be deduced about the structure of the atom from this?
How do you explain why puddles evaporate on cold days ?
A basketball player throws his ball vertically upwards with an initial speed of v=40 m/s. Ignore air resistance. What is the speed of the ball at half of the maximum height?
A cricketer throws a ball vertically upwards so that the ball leaves his hands at a speed of 25 m/s. Calculate the maximum height reached by the ball, the time taken to reach max. height, and the speed of the ball when it is at 50% max. height.