Physics Unit 2 Revision (Higher tier)

days the radiation will fallen by half again and reached 20 counts perminute.If we have a substance which has a mass of 50g and a half life of 2 days howwould the mass of the substance change?After 2 days the mass would be 25g (half of 50g). 25 g has radiated away.After 4 days the mass would be 12.5g (half of 25g). 37.5g has radiated away.After 6 days the mass would be 6.25g (half of 12.5g). 43.75g has radiated awayand so onUses of radioactive decayPeople who work with radioactive sourceoften were special badges. These badgeshave a special photographic film in themwhich turns darker the bigger theexposure. Radioactive sources can beused as tracers. They can be added toplant fertiliser and you can then check ifthe plant has taken up the fertiliser. It isalso used in the medical industry butdoctors must ensure that it has a short half life so that it doesn’t stay in thebody very long and cause damage.Alpha sources are used in smokedetectors. The alpha particleshelp to create an electriccurrent in the smoke detector byionising the air. When smokeparticles enter the smokedetector the electric currentdrops, this causes the alarm togo off.