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 Nis 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 Nyou may find λ and follow the previous steps.

*Make sure you familiar with exponentials and logs before attempting this topic

JS
Answered by Joe S. Physics tutor

13979 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

A small ball of mass 150 g is placed at a height of 20cm above the ground on an incline of 35°. It is released and allowed to roll down the slope; what will be the ball's speed when it reaches the ground? Assume friction and air resistance can be ignored.


How did rutherford's gold leaf experiment prove the existence of the nucleus?


An ultraviolet wave of continuous frequency reflects from a solid surface back in the direction of the transmitter. Assuming no amplitude is lost, describe and explain the behaviour of the particles in the medium between the transmitter and surface.


State similarity and difference between the electric field lines and the gravitational field lines around an isolated positively charged metal sphere.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences