what is a half life of a substance and how can you work it out.

A half life of a substance is the time it takes for the mass of a radioactive substance to decrease by half. Say you have 50g of carbon-14, you are looking for the amount of time it takes for the mass to reach 25g of this isotope.
Say we have 200g carbon-14, and it has a hypothetical half-life of 5 years. How much will be left after 20 years?So, we do 20/5=4, so we have 4 half lives undertaken. If a half life is dividing the mass by 2, each progressive half life also decreases the mass by dividing it by 2. So, we can think of dividing our original amount by 2^n, where n is the number of half lives passed. Therefore, we have 200/(2^4) or 200/16, which equals 12.5g remaining of carbon-14.

SW
Answered by Samuel W. Physics tutor

1648 Views

See similar Physics GCSE tutors

Related Physics GCSE answers

All answers ▸

Why do things get hot when electricity is pasted through them?


An electric Iron rated at 2600 W contains a steel plate, heated to a working temperature of 215°C. Room temp=18°C. Deduce whether the plate could reach its working temperature in less than 1 minute. Mass (steel plate)=890g & C (steel)=450J/kg/K


What is the doppler effect?


how do i calculate acceleration?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences