Question: How can you prove a half life?

Sarah Hunak answered on 16 Nov 2016:

Hi, I’ve answered a similar question so I”ll copy the reply in here too….

A half life is the time taken for a radioactive material to lose half of it’s activity. So when something is radioactive, it gives off radiation ,and the amount of radiation is called its activity. Over time, this activity falls and the radioactive particles stop being radioactive. If the half life of a radioactive material is for example 5 years, then if the starting activity was 100 Bq (Bequerel is the unit of radiation), then after 5 years, the activity would be 50 Bq. Then after another 5 years, so 10 years in total, it would be 25 Bq, after another 5 years, 17.5 Bq and so on.

the half life of a radioactive material depends on what the material is. Some have half lives of only a few seconds, some have half lives of thousands of years!

It’s not the easiest subject to get your head around, you’ll learn more about it when you do your GCSEs, but great question, thanks!

You can prove it because we are able to measure the activity of something using radiation detection instruments so we can see if it works or not.

To demonstrate it, try to follow this lesson plan I wrote for the Society of Radiological Protection.
https://srp-uk.org/_getDocument/934
This is one of the demonstrations we do in our schools lecture but you could try it in your classroom with Skittles. When I teach this at work, I use Skittles, then we get to eat them afterwards 🙂
As I said before, it’s an excellent question and you will learn about it at GCSE so don’t worry too much if the lesson plan doesn’t all make sense.