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## Half life

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**Half life**Exponential functions**Half Life**[ Definition : Half-life- the time it takes for one-half of the atoms of an unstable element or nuclide to decay radioactively into another element or nuclide. ]**Radium has a half life of 1600 years. If A0 = 8 grams,**show that the decay function for the mass remaining after n years is given by Use this function to find the mass left after (i) 40 years (ii) 200 years**A radioactive element has a half life of only 20 years.**Write down a decay function for 40 grams of the material after n years. a) Calculate the mass left after 15 years. b) Calculate the mass left after 45 years.**The half life of C14 the radioactive form of carbon is 5730**years. If 5 gram of carbon is initially present, construct a decay function that models the amount left after n years. How much will be left after 10000 years?**The table shows some materials,**their half lives and their area of application. Use this table to answer the questions on the next slide.**For each material set up a decay function**for 50 grams of the material. Use these decay functions to answer the following questions. How much Iodine – 123, is left after 1 day? How much Cobalt -60, is left after 8 years? How much Plutonium-239, is left after 1000 years?