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Activity & decay

Long half lives are measured using the principle of activity. If 3.0mg of 239Pu has an activity of 6.9×106Bq, calculate the half life of 239Pu. Give your answer in years to 2 significant figures (strictly the answer to this question should be given to 1 sig fig, but 2 sig figs allows us to check your method is correct)

Reply 1

http://physicsnet.co.uk/a-level-physics-as-a2/radioactivity/radioactive-decay/

Use the equations available here and have a go

Reply 2

OP

Original post by Jakir

http://physicsnet.co.uk/a-level-physics-as-a2/radioactivity/radioactive-decay/

Use the equations available here and have a go

I've tried it twice and got 7.6x10^11 seconds both times but it days that it is wrong.

(edited 6 years ago)

Reply 3

Study Forum Helper

Original post by Katie2000

I've tried it twice and got 7.6x10^11 seconds both times but it days that it is wrong.

Hi, it would be good that you show your working and the number that you use to calculate.

Reply 4

For the next person struggling:
Dont forget to divide your answer by 3.16 x 10⁷. They want the answer in years.

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