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Do Now Copy and complete : page 265 The ________ of a radioactive substance is the average time taken for half of the _______of the substance to decay. It is also equal to the average time taken for the ________ of the substance to halve. The half-life of carbon 14 is about _______ years. If today a sample of carbon 14 has an activity of 3400 Bq then in 5600 years time this should have fallen to ______ Bq. 11200 years later the activity should have fallen to ____ Bq. The number of carbon 14 nuclei would have also decreased by ______ times. eighthalf-life5600425activity1700 WORD & NUMBER SELECTION: nuclei eight half-life 5600 425 activity 1700 nuclei
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Today’s lesson Find the half life from graphs version 2. Give and explain examples of practical applications of isotopes. Title Uses of radioactive isotopes
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Finding half-life from a graph half-life The half-life in this example is about 30 seconds. A more accurate value can be obtained be repeating this method for a other initial nuclei numbers and then taking an average.
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Question 6 Estimate the half-life of the substance whose decay graph is shown opposite. half-life
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Revision Simulations Half-LifeHalf-Life - S-Cool section on half-life and uses of radioactivity including an on- screen half-life calculation and an animation showing thickness control. BBC AQA GCSE Bitesize Revision: Detecting radiation Natural sources of background radiation Artificial radiation Half life Alpha DecayAlpha Decay - PhET - Watch alpha particles escape from a Polonium nucleus, causing radioactive alpha decay. See how random decay times relate to the half life.
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Title Uses of radioactive isotopes
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Smoke detection Uses
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Thickness control
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Used as Tracers
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Killing microbes
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Checking welds
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Used as TracersTracers
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Carbon dating
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“Can you………?” Bring in your exercise books on Thursday 27 th Sept.
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Test! Thursday 27 th September 2012 I will collect your Exercise books on Thursday – Remember them!
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Can you answer the all the questions on pages 265 and Q5,7,8,9 &10 page 270?
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