What is "half-life"?

Half-life is a term commonly used in radioactivity. It defines the time taken for a radioactive source to halve its activity. A radioactive source will emit radiation (energy) through the emission of particles or photons. How many of these particles are being released every second (or any arbitrary unit of time) determines a substance's activity. This can be seen mathematically through analysing the radioactive decay equations listed in the AQA formula list here: http://filestore.aqa.org.uk/subjects/AQA-PHYA4-5-INS-JUN12.PDF. Furthermore, the maths used to derive the equation for half-life, can be explained through these equations; I would be happy to show you if you wish. In conclusion, half life is how long it takes for a radioactive substance to become half as radioactive as it initially was. 

Answered by Evan T. Physics tutor

4195 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

Use the kinetic theory of gases to explain why the pressure inside a container increases when the temperature of the air inside it rises. Assume that the volume of the container remains constant.


Why does Lenz's law have a minus sign?


A roller coaster has a loop, r = 20m, how fast should it travel so that riders don't fall out?


A conical pendulum is a mass suspended from a point that traces out a horizontal circle. By balancing the weight with the tension in the string, determine the speed of the bob.


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