Half-life (Edexcel GCSE Physics Combined Science): Flashcards
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Practise the cards
12 cards from this deck
Definition of half-life
Definition of half-life
Time for half of unstable nuclei in a sample to decay
Activity after each half-life
Activity after each half-life
Decreases by half
Unit for measuring radioactive activity
Unit for measuring radioactive activity
Becquerels (Bq)
Meaning of 1 Bq
Meaning of 1 Bq
One decay per second
Nature of radioactive decay
Nature of radioactive decay
Random process
Can we predict when an individual atom will decay?
Can we predict when an individual atom will decay?
No - decay is random
After one half-life, fraction of nuclei remaining
After one half-life, fraction of nuclei remaining
Half (50%)
Activity after 1 half-life
Activity after 1 half-life
Half the original activity
After 2 half-lives, activity is what fraction?
After 2 half-lives, activity is what fraction?
One quarter (25%) of original
How to calculate number of half-lives
How to calculate number of half-lives
Time elapsed half-life period
After 4 half-lives, what fraction remains?
After 4 half-lives, what fraction remains?
rac{1}{16} of original
How to find half-life from a graph
How to find half-life from a graph
Find time for count to halve from initial value