Transcript
Half-Life Estimated completion time: 1 hour Website: https://www.thephysicsaviary.com/Physics/Programs/Labs/Half-LifeLab/index.html Introduction: What is radioactive decay? List some of the different types of radioactive materials. What is the half-life of a substance? Procedure: In this lab you will be looking at the amount of radiation you detect from a radioactive source as a function of time. When you start this lab, you will have a freshly made sample of Bi-211. Read all of the instructions before clicking begin, as the simulator will begin running immediately. Click the link to go to the simulator and click begin. Clicking on the activity in the upper left corner of the lab will give you a fresh sample of your isotope. Find the sample with the greatest activity and use it for your lab. It should be about 230 decay/second. Your isotope will be decaying the moment you create it, so be prepared as to what you must do to properly collect your data. Allow your decade counter to count radioactive decay particles for 10 seconds and then hit the "hold button". In your data table record this as time = 0 and counts equal to your counts for that 10 second interval. *The sample time will pause when you press hold, but the total time will continue running.* When the total time reaches 60 seconds, click the reset button on the decade counter (this will turn off hold and immediately begin the sample time counter) and collect data for another 10 seconds. In your data table record this as time = 60 and counts equal to your counts for that 10 second interval. Continue to collect 10 s worth of data at the start of each new minute until you have collected a total of 10 data points. For example, you will press hold at 70 seconds, record your data and then press reset at 120 seconds to begin collecting a count number for the 120-130 second timeframe. Continue doing this for each minute until the data table below is full. Plot a graph of Counts vs. Time (s) and curve fit it with an exponential function. When you have collected your data, graph it on an xy scatter plot (in Word go to the ‘Insert’ tab and click ‘Chart’. A small excel window will appear; enter your data into it to create the graph. Once the graph is complete, right click the data points and add a trend line. Set the trend line to exponential. If you mess up, click the sample in the top left again to restart, or refresh the web page. If you are having trouble understanding the instructions, this video may clarify certain points: https://www.youtube.com/watch?v=tT4W_joOtKM&feature=youtu.be Data: Total time (s) Counts in 10 seconds 0 60 120 180 240 300 360 420 480 540 Graph: Insert your graph here. Analysis and Conclusion: Using your graph, and knowledge of a half-life, estimate the approximate half-life of your Bismuth 211 sample. What does it mean when we say an atom has ‘decayed’? How do scientists use radioactive decay to date fossils and artifacts? Write a 1-2 paragraph conclusion discussing your data, sources of error, and what you learned in this lab.
