Difference between revisions of "Half Life"
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==Key Stage 4== | ==Key Stage 4== | ||
===Meaning=== | ===Meaning=== | ||
| + | [[File:HalfLifeGraph1.png|right|300px|thumb|A [[graph]] showing the [[fraction]] of [[Unstable Isotope|unstable isotope]] left compared to the '''half life'''.]] | ||
A '''half life''' is the time it takes for half of the [[Unstable Isotope|unstable isotopes]] in a [[radioactive]] sample to [[Radioactive Decay|decay]]. | A '''half life''' is the time it takes for half of the [[Unstable Isotope|unstable isotopes]] in a [[radioactive]] sample to [[Radioactive Decay|decay]]. | ||
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: The '''half life''' of an [[isotope]] depends on how [[Stable Isotope|stable]] the [[isotope]] is. | : The '''half life''' of an [[isotope]] depends on how [[Stable Isotope|stable]] the [[isotope]] is. | ||
: The '''half life''' of an [[isotope]] can be determined by measuring the [[emission]] of [[Ionising Radiation|ionising radiation]]. The time it takes for the [[Count Rate|count rate]] of [[Ionising Radiation|ionising radiation]] to halve, is the same as its '''half life'''. | : The '''half life''' of an [[isotope]] can be determined by measuring the [[emission]] of [[Ionising Radiation|ionising radiation]]. The time it takes for the [[Count Rate|count rate]] of [[Ionising Radiation|ionising radiation]] to halve, is the same as its '''half life'''. | ||
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| + | |[[File:UnstableIsotopeDecay.png|center|600px]] | ||
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| + | | style="height:20px; width:200px; text-align:left;" |This [[diagram]] shows the number of [[Fermium]]-252 [[atom]]s halves each day, so the '''half life''' is 1 day. | ||
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Revision as of 11:28, 9 March 2019
Key Stage 4
Meaning
A half life is the time it takes for half of the unstable isotopes in a radioactive sample to decay.
About Half Life
- Every isotope has a unique half life.
- The half life of an isotope depends on how stable the isotope is.
- The half life of an isotope can be determined by measuring the emission of ionising radiation. The time it takes for the count rate of ionising radiation to halve, is the same as its half life.
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| This diagram shows the number of Fermium-252 atoms halves each day, so the half life is 1 day. |
| Time /s | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
| Count rate /Bq | 1000 | 707 | 500 | 353 | 250 | 176 | 125 | 88 | 62 |
| Time /min | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Count rate /Bq | 5000 | 3968 | 3150 | 2500 | 1984 | 1575 | 1250 | 992 | 788 |