PhET/C3/Rutherford-Scattering/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to this tutorial on Rutherford Scattering simulation. |
| 00:06 | In this tutorial, we will demonstrate Rutherford Scattering, PhET simulation. |
| 00:13 | Here I am using-
Ubuntu Linux OS version 14.04, |
| 00:20 | Java version 1.7.0, |
| 00:25 | Firefox Web Browser version 53.02.2 |
| 00:31 | To follow this tutorial, learner should be familiar with topics in high school science. |
| 00:39 | Using this simulation, we will learn: about Plum pudding and Rutherford atomic models, |
| 00:48 | to visualize the Rutherford gold foil experiment, |
| 00:52 | about behavior of alpha particles, |
| 00:56 | to identify the factors that affect the deflection of alpha particles. |
| 01:02 | Now let us start the demonstration. |
| 01:06 | Use the given link to download the simulation. |
| 01:11 | I have already downloaded Rutherford Scattering simulation to my Downloads folder. |
| 01:18 | To open the simulation, right click on Rutherford Scattering html file. |
| 01:26 | Select Open with Firefox Web Browser option. |
| 01:30 | File opens in the browser. |
| 01:33 | This is the interface of Rutherford Scattering simulation. |
| 01:38 | The interface has 2 screens- Rutherford Atom, Plum Pudding Atom. |
| 01:45 | Let's begin with Plum Pudding Atom screen. |
| 01:49 | J. J. Thomson proposed Plum Pudding atomic model. |
| 01:53 | This model was proposed before Rutherford's atomic model. |
| 01:58 | Click on Plum Pudding Atom screen to open it. |
| 02:02 | Left side of the screen has experimental set up for Plum Pudding atomic model. |
| 02:09 | It consists of thin sheet of a metal above the Alpha Particles source. |
| 02:15 | Center of the screen has view box. |
| 02:19 | It shows a single atom with 3 into 10 to the power of -10 meter atomic scale. |
| 02:26 | In the atom, red portion represents the positive charge which is uniformly distributed. |
| 02:33 | Small blue spheres represent electrons which are embedded in the atom. |
| 02:39 | There is no separation between positive charge and electrons in the atom. |
| 02:44 | Screen on the right side shows 2 boxes, Legend and Alpha particle. |
| 02:53 | Legend box helps to identify the key components of the atom. |
| 02:58 | Alpha Particle box consists of- an Energy slider to change the energy of incoming alpha particles, |
| 03:06 | Traces check-box to show an alpha particle's trajectory. |
| 03:11 | Check the Traces check-box. |
| 03:14 | Bottom of the screen we have, Play/Pause button, |
| 03:19 | Step button and Reset button. |
| 03:23 | To turn on the Alpha Particles source, click on the blue button. |
| 03:28 | Notice that alpha particles beam strikes the thin metal foil. |
| 03:33 | Observe the path of alpha particles inside the atom. |
| 03:37 | All the alpha particles pass through the atom un-deflected. |
| 03:42 | This is because electrons are distributed evenly throughout the atom. |
| 03:47 | The magnitude of negative and positive charges inside the atom is equal. |
| 03:53 | This gives the most stable electrostatic arrangement. |
| 03:57 | Therefore it makes an atom electrically neutral. |
| 04:01 | Plum Pudding model was able to explain overall neutrality of the atom. |
| 04:07 | Plum Pudding model of an atom failed to explain:
the stability of an atom, |
| 04:15 | position of the nucleus in an atom. |
| 04:19 | Plum Pudding model could not account for the atomic structure. |
| 04:24 | But it provided the base for the development of other atomic structure models. |
| 04:31 | Let's move on to Rutherford Atom screen. |
| 04:35 | Click on Rutherford Atom screen to open it. |
| 04:39 | Rutherford Atom screen helps to visualise the rutherford's gold foil experiment. |
| 04:45 | Rutherford Atom screen has same tools as that of Plum Pudding atom screen. |
| 04:51 | Additionally, there is an Atom box below Alpha Particle box. |
| 04:56 | Atom box consists of Protons and Neutrons sliders to change the composition of the nucleus. |
| 05:04 | Here, number of protons and neutrons is equal to that of gold atom. |
| 05:09 | At the centre of the screen, you will see a box. |
| 05:13 | It represents a zoom in view of different atoms in the gold foil. |
| 05:19 | Left side of the screen has 2 model views. |
| 05:23 | They are atomic view and nuclear view. |
| 05:27 | By default, atomic view is selected. |
| 05:31 | Atomic view gives an idea about the behavior of alpha particles as they travel through the atom. |
| 05:38 | Click on blue button to turn on the Alpha particles source. |
| 05:43 | Notice that alpha particles beam strikes the thin gold foil. |
| 05:48 | Check the Traces check-box to see the trajectories of alpha particles. |
| 05:54 | Observe the traces of alpha particles as they approach the nuclei of the atoms. |
| 06:00 | Now, pause the simulation and click on Step button. |
| 06:06 | Here, Most alpha particles are undeflected. |
| 06:11 | Some of the alpha particles are slightly deflected. |
| 06:15 | A very few alpha particles bounce back, that is, deflected by nearly 180°. |
| 06:22 | Let's see the behaviour of alpha particles in nuclear view. |
| 06:27 | Click on nuclear view. |
| 06:29 | Notice that in zoom in view, atoms are replaced by a single nucleus. |
| 06:35 | Now play the simulation. |
| 06:38 | Observe the deflections of alpha particles as they approach the nucleus. |
| 06:44 | Here n/p ratio for the gold atom is 1.5. Therefore alpha particles show a large deflection. |
| 06:53 | Let's study the factors that affect the scattering of alpha particles. |
| 06:59 | Drag the Energy slider towards minimum. |
| 07:03 | Observe that angles of deflection increases with the decrease in energy. |
| 07:09 | Next we will see, how change in composition of nucleus affects scattering of alpha particles. |
| 07:16 | Let's start with small nucleus with few number of protons and neutrons. |
| 07:22 | Drag the Energy slider back to its default position. |
| 07:27 | Then drag the Protons and Neutrons sliders towards 20. |
| 07:32 | Size of the nucleus becomes small. |
| 07:35 | Observe the angles of deflection of alpha particles. |
| 07:39 | Angle of deflection decreases with the decrease in protons and neutrons number. |
| 07:45 | Here atom is stable as n /p ratio is 1. |
| 07:50 | Observe that alpha particles far from the nucleus have almost no detectable deflection. |
| 07:57 | While the alpha particles that are close to the nucleus are deflected. |
| 08:02 | As an assignment, try various combinations of protons and neutrons and check the deflections. |
| 08:10 | Give an explanation for the change in the behaviour of the alpha particles. |
| 08:16 | Let us summarise. |
| 08:19 | In this tutorial, we have demonstrated how to use Rutherford Scattering, PhET simulation. |
| 08:28 | Using this simulation, we have learnt: about Plum pudding and Rutherford atomic models, |
| 08:37 | to visualize the Rutherford gold foil experiment, |
| 08:41 | about behavior of alpha particles, |
| 08:45 | to identify the factors that affect the deflection of alpha particles. |
| 08:51 | The video at the following link summarizes the Spoken Tutorial project. Please download and watch it. |
| 09:00 | The Spoken Tutorial Project team conducts workshops using spoken tutorials and gives certificates on passing online tests. |
| 09:09 | For more details, please write to us. |
| 09:13 | Please post your timed queries on this forum. |
| 09:17 | This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. |
| 09:25 | Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
More information on this mission is available at this link. |
| 09:38 | This is Meenal Ghoderao from IIT Bombay.
Thank you for joining. |
