PhET-Simulations-for-Biology/C3/Radioactive-Dating-game/English-timed

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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.

Contributors and Content Editors

Nancyvarkey