PhET-Simulations-for-Biology/C3/Radioactive-Dating-game/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to this tutorial on Radioactive Dating Game, an interactive PhET simulation. |
| 00:08 | In this tutorial, we will demonstrate, Radioactive Dating Game, an interactive PhET simulation. |
| 00:17 | Here I am using,
Ubuntu Linux OS version 16.04 Java version 1.8.0 Firefox Web Browser version 60.0.2 |
| 00:32 | Learners should be familiar with high school physics and chemistry. |
| 00:37 | Using this simulation, we will look at
Radioactive decay and half life Decay rates Measurement of radioactivity Radioactive dating |
| 00:51 | Please refer to the additional material provided with this tutorial. |
| 00:55 | Let us begin. |
| 00:58 | Use the given link to download the simulation. |
| 01:02 | I have already downloaded the Radioactive Dating Game simulation to my Downloads folder. |
| 01:10 | To open the jar file, open the terminal. |
| 01:14 | At the terminal prompt, type cd Downloads and press Enter. |
| 01:22 | Type java space hyphen jar space radioactive-dating-game underscore en dot jar, press Enter. |
| 01:36 | File opens in the browser in html format. |
| 01:41 | This is the interface for the Radioactive Dating Game simulation. |
| 01:46 | Now we will explore the interface. |
| 01:49 | The interface has four screens:
Half Life Decay Rates Measurement Dating Game |
| 02:00 | We are already looking at the Half Life screen. |
| 02:04 | At the top of the screen is an Isotope versus Time graph. |
| 02:09 | Pay attention to the units of time. |
| 02:12 | On the right side of the screen, you see a Choose Isotope panel. |
| 02:17 | It has three options showing unstable nucleus decaying to stable nucleus. |
| 02:25 | In the middle is the simulation panel containing a Bucket o’ Atoms. |
| 02:31 | Note that it contains C-14 atoms as the default selection is C-14. |
| 02:38 | Attached to the bottom of the bucket is a button called “Add 10”. |
| 02:44 | Stable and Unstable Nuclei
The strong nuclear force overcomes the electrostatic repulsion between protons. |
| 02:54 | The energy associated with this force is the binding energy. |
| 03:00 | The lower the binding energy, the more unstable is the nucleus. |
| 03:06 | Such an unstable nucleus is said to be radioactive. |
| 03:12 | Below the simulation panel is a Play/Pause button and a Step button next to it. |
| 03:19 | In the simulation panel is a blue Reset All Nuclei button. |
| 03:25 | It lets you return to the start but with the selected isotope. |
| 03:30 | Below the right panel is a white Reset All button. |
| 03:35 | It resets the simulation in this screen to all the default settings. |
| 03:41 | Observe the Isotope versus time graph. |
| 03:45 | There is a vertical red dashed line labeled Half Life near the 5000 year mark. |
| 03:52 | The half-life of C-14 is 5730 years. |
| 03:58 | Along the y-axis, you can see the red C-14 symbol above the blue N-14 symbol. |
| 04:06 | C-14 atoms will appear in the upper row and N-14 atoms in the lower one. |
| 04:13 | To the left of the Isotope label is a red circle. |
| 04:17 | Numbers of C-14 and N-14 atoms shown by hash symbols will appear to the left of the circle. |
| 04:26 | Radioactive Decay
Radioactive Decay is the spontaneous conversion of an unstable nucleus into a stable nucleus. |
| 04:36 | It involves the release of subatomic particles and their energy as radiation. |
| 04:43 | It is of the following types:
Alpha decay Beta decay Gamma decay. |
| 04:52 | Half-life is the time taken for half of the nuclei in a radioactive material to decay. |
| 05:01 | Let us get back to the simulation. |
| 05:04 | Click on Add 10 and immediately click on the Pause button. |
| 05:10 | Ten C-14 atoms have been added to the simulation panel. |
| 05:15 | Almost immediately, red C-14 has started to decay to give blue N-14. |
| 05:22 | Observe the atoms moving across the graph in the two rows. |
| 05:28 | Note how the circle changes to blue as more N-14 atoms form. |
| 05:34 | Keep clicking on Step button to the right of Pause. |
| 05:42 | The circle is half red and half blue. |
| 05:47 | Observe that there are 5 blue N-14 atoms in the graph. |
| 05:54 | There are 5 C-14 atoms and 5 N-14 atoms in the simulation panel also. |
| 06:01 | This is the definition of half-life. |
| 06:04 | If you click again on Add 10, another 10 C-14 atoms will be added to the simulation panel. |
| 06:12 | Predict the number of C-14 atoms remaining after different periods. |
| 06:18 | Perform the same simulation for the other nuclei. |
| 06:23 | Click on the Decay Rates tab to go to that screen. |
| 06:28 | The interface has a similar arrangement as the Half Life screen. |
| 06:33 | Please explore this screen in the same way. |
| 06:37 | Now, let us click on the Measurement tab to go to that screen. |
| 06:42 | In the right panel, under Choose an Object, we will stay with Tree, the default selection. |
| 06:50 | In the top left, under Probe Type, we will retain the default selections, Carbon-14 and Objects. |
| 06:59 | In the bottom right corner, click on Plant Tree button. |
| 07:04 | Immediately click on the Pause button. |
| 07:07 | Observe 100% appear above Probe Type in the upper left corner. |
| 07:14 | Keep clicking on the Step button to the right of Pause to move the simulation along. |
| 07:23 | Above the graph, % of C-14 is the default selection. |
| 07:29 | The white box below the graph shows the number of years since the tree was planted. |
| 07:35 | The red line shows % of C-14 remaining in the tree. |
| 07:41 | Click on the second C-14 to C-12 ratio radio button above the graph. |
| 07:48 | Now the red line shows the C-14 to C-12 ratio in the tree. |
| 07:53 | Click again on the % of C-14 radio button above the graph. |
| 07:58 | Keep track of the % in the top left, the tree and the number of years below the graph. |
| 08:09 | Note down the number of years and % of C-14 when the tree
Loses its green color Loses all its leaves Falls over. |
| 08:20 | Click on the Play or Step buttons to get approximately 50% in the top left window. |
| 08:35 | Note the number of years after which you see 50% of C-14 in the tree. |
| 08:42 | Click on Rock and Uranium-238 radio buttons. |
| 08:50 | Click on Erupt Volcano and Cool rock buttons. |
| 08:58 | Measure U-238 levels in the cooled volcanic rock. |
| 09:04 | Click on the Air radio button to compare isotope levels in objects to air levels. |
| 09:12 | Let us click on the last Dating Game tab to go to that screen. |
| 09:17 | We can measure levels of C-14, U-238 or other custom nuclei in this screen. |
| 09:25 | We see objects on and below the ground on which we can place the probe to measure these levels. |
| 09:34 | Radioactive Dating
Carbon has two isotopes: C-12 and C-14. |
| 09:41 | Both are converted to carbon dioxide and are taken in by living organisms. |
| 09:47 | When an organism dies, it no longer takes in any carbon. So levels of C-14 and ratio of C-14 to C-12 fall. |
| 09:57 | Radioactive Dating-Continued
Radioactive dating compares C-14 C-12 ratio of samples to recently dead specimens. |
| 10:06 | It estimates how long the organism has been dead. |
| 10:10 | Uranium-lead dating is used for rocks, archaeological artefacts etc. |
| 10:17 | On the top, we see the graph like the ones in the previous screens. |
| 10:22 | Let us keep the following default selections:
Under Probe Type, Carbon-14 Objects % of C-14 |
| 10:33 | We will drag the probe and place it on the animal skull on the ground, to the left. |
| 10:40 | Observe a pop-up box that appears next to the skull. |
| 10:45 | We see the text, “Estimate age of Animal Skull” and “years” next to the empty box below. |
| 10:53 | Below this is a Check Estimate button. |
| 10:57 | Observe that in the top left side, above Probe Type, we see 98.2%. |
| 11:04 | Let us drag the double-headed green arrow above the graph. |
| 11:09 | In the white box above the arrow, % of C-14 should be approximately 98.2%. |
| 11:18 | Observe that t equals 123 yrs appears in the white box above the graph. |
| 11:26 | Type 123 in the empty box below Estimate age of Animal Skull. |
| 11:33 | Click Check Estimate button. |
| 11:36 | The Estimate pop-up box disappears. |
| 11:40 | A green text-box with 123 years appears in its place with a green smiley face next to it. |
| 11:48 | We have successfully dated the animal skull by measuring the % of C-14 remaining in it. |
| 11:56 | As an assignment,
Estimate ages of all the objects in the Dating Game screen. |
| 12:03 | Correlate age in years with percentage of unstable nucleus. |
| 12:08 | Correlate age in years with the depth at which the object is found. |
| 12:13 | Remember to use C-14 for animal remains and U-238 for rocks and other objects. |
| 12:20 | Let us summarize. |
| 12:22 | In this tutorial, we have demonstrated how to use the Radioactive Dating Game PhET simulation. |
| 12:31 | Using this simulation, we looked at:
Radioactive decay and half life Decay rates Measurement of radioactivity Radioactive dating |
| 12:46 | The video at the following link summarizes the Spoken Tutorial project. |
| 12:52 | Please download and watch it. |
| 12:55 | The Spoken Tutorial Project team conducts workshops using spoken tutorials and gives certificates on passing online tests. |
| 13:04 | For more details, please write to us. |
| 13:08 | Please post your timed queries in this forum. |
| 13:12 | This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. |
| 13:20 | Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. |
| 13:28 | More information on this mission is available at this link. |
| 13:33 | This is Vidhya Iyer from IIT Bombay, signing off. |
| 13:37 | Thank you for joining. |
