View source for PhET/C3/Rutherford-Scattering/English-timed

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||'''Time'''
||'''Narration'''

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|| 00:01
|| Welcome to this tutorial on '''Rutherford Scattering simulation'''.

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||00:06
|| In this tutorial, we will demonstrate '''Rutherford Scattering''', '''PhET simulation'''.

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|| 00:13
|| Here I am using- 

'''Ubuntu Linux OS''' version 14.04,

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|| 00:20
||'''Java''' version 1.7.0,

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|| 00:25
||'''Firefox Web Browser''' version 53.02.2

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|| 00:31
|| To follow this tutorial, learner should be familiar with topics in high school science.

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|| 00:39
|| Using this '''simulation''', we will learn: about '''Plum pudding''' and '''Rutherford''' atomic models,

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|| 00:48
||to visualize the '''Rutherford gold foil''' experiment,

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|| 00:52
||about behavior of '''alpha''' particles,

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|| 00:56
||to identify the factors that affect the deflection of '''alpha''' particles.

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|| 01:02
|| Now let us start the demonstration.

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|| 01:06
|| Use the given '''link''' to download the '''simulation'''.

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|| 01:11
|| I have already downloaded '''Rutherford Scattering simulation''' to my '''Downloads''' folder.

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|| 01:18
|| To open the '''simulation''', right click on '''Rutherford Scattering''' html file.

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|| 01:26
||Select '''Open with Firefox Web Browser''' option.

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|| 01:30
||File opens in the browser.

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|| 01:33
|| This is the interface of '''Rutherford Scattering simulation'''.

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|| 01:38
|| The interface has 2 '''screen'''s- '''Rutherford Atom''', '''Plum Pudding Atom'''.

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|| 01:45
|| Let's begin with '''Plum Pudding Atom''' screen.

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|| 01:49
||J. J. Thomson proposed '''Plum Pudding''' atomic model.

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|| 01:53
||This model was proposed before '''Rutherford's''' atomic model.

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|| 01:58
|| Click on '''Plum Pudding Atom''' screen to open it.

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|| 02:02
|| Left side of the screen has experimental set up for '''Plum Pudding''' atomic model.

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|| 02:09
|| It consists of thin sheet of a metal above the '''Alpha Particles''' source. 

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|| 02:15
|| Center of the screen has '''view box'''.

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|| 02:19
||It shows a single atom with '''3 into 10 to the power of  -10 meter atomic scale'''.
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|| 02:26
|| In the atom, red portion represents the positive '''charge''' which is uniformly distributed. 

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|| 02:33
||Small blue spheres represent electrons which are embedded in the atom.

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|| 02:39
||There is no separation between positive charge and electrons in the atom.

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|| 02:44
|| '''Screen''' on the right side shows 2 boxes, '''Legend''' and '''Alpha particle'''.

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|| 02:53
|| '''Legend''' box helps to identify the key components of the atom.

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|| 02:58
|| '''Alpha Particle''' box consists of- an '''Energy''' slider to change the energy of incoming alpha particles,

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|| 03:06
||'''Traces''' check-box to show an '''alpha''' particle's trajectory.

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|| 03:11
||Check the '''Traces''' check-box.

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|| 03:14
|| Bottom of the screen we have, '''Play'''/'''Pause''' button, 

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|| 03:19
||'''Step''' button and '''Reset''' button.

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|| 03:23
|| To turn on the '''Alpha Particles''' source, click on the blue button.

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|| 03:28
|| Notice that '''alpha''' particles beam strikes the thin metal foil.

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|| 03:33
|| Observe the path of '''alpha''' particles inside the atom.

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|| 03:37
|| All the '''alpha''' particles pass through the atom un-deflected.

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|| 03:42
|| This is because electrons are distributed evenly throughout the atom.

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|| 03:47
||The magnitude of negative and positive '''charge'''s inside the atom is equal.

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|| 03:53
||This gives the most stable '''electrostatic''' arrangement.

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|| 03:57
||Therefore it makes an atom electrically neutral.

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|| 04:01
|| '''Plum Pudding''' model was able to explain overall neutrality of the atom.

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|| 04:07
|| '''Plum Pudding''' model of an atom failed to explain: 

the stability of an atom, 

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|| 04:15
|| position of the nucleus in an atom.

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|| 04:19
|| '''Plum Pudding''' model could not account for the atomic structure.

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|| 04:24
||But it provided the base for the development of other atomic structure models.

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|| 04:31
|| Let's move on to '''Rutherford Atom''' screen.

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|| 04:35
|| Click on '''Rutherford Atom''' screen to open it.

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|| 04:39
|| '''Rutherford Atom''' screen helps to visualise the rutherford's gold foil experiment.

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||04:45
|| '''Rutherford Atom''' screen has same tools as that of '''Plum Pudding''' atom screen.

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|| 04:51
||Additionally, there is an '''Atom''' box below '''Alpha Particle''' box.

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||04:56
|| '''Atom''' box consists of '''Protons''' and '''Neutrons''' sliders to change the composition of the nucleus. 

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|| 05:04
||Here, number of '''protons''' and '''neutrons''' is equal to that of gold atom.

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|| 05:09
|| At the centre of the screen, you will see a box.

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|| 05:13
||It represents a '''zoom in''' view of different atoms in the gold foil.

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|| 05:19
|| Left side of the screen has 2 model views. 

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|| 05:23
||They are '''atomic view''' and '''nuclear view'''.

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|| 05:27
|| By default, '''atomic view''' is selected.

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|| 05:31
||'''Atomic view''' gives an idea about the behavior of '''alpha''' particles as they travel through the atom.

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|| 05:38
|| Click on blue button to turn on the''' Alpha particles''' source.

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|| 05:43
||Notice that '''alpha''' particles beam strikes the thin gold foil.

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|| 05:48
|| Check the '''Traces''' check-box to see the trajectories of '''alpha''' particles.

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|| 05:54
|| Observe the traces of '''alpha''' particles as they approach the nuclei of the atoms.

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||06:00
|| Now, pause the '''simulation''' and click on '''Step''' button.

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|| 06:06
|| Here, Most '''alpha''' particles are undeflected.

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|| 06:11
||Some of the '''alpha''' particles are slightly deflected.

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|| 06:15
||A very few '''alpha''' particles bounce back, that is, deflected by nearly 180°.

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|| 06:22
|| Let's see the behaviour of '''alpha''' particles in '''nuclear view'''.

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|| 06:27
||Click on '''nuclear view'''.

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|| 06:29
||Notice that in '''zoom in view''', atoms are replaced by a single nucleus.

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|| 06:35
|| Now play the '''simulation'''.

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|| 06:38
|| Observe the deflections of '''alpha''' particles as they approach the nucleus.

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||06:44
|| Here n/p ratio for the gold atom is 1.5. Therefore '''alpha''' particles show a large deflection.

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|| 06:53
|| Let's study the factors that affect the scattering of '''alpha''' particles.

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|| 06:59
|| Drag the '''Energy''' slider towards '''minimum'''.

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|| 07:03
||Observe that angles of deflection increases with the decrease in energy. 

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|| 07:09
|| Next we will see, how change in composition of nucleus affects scattering of '''alpha''' particles.

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|| 07:16
|| Let's start with small nucleus with few number of '''protons''' and '''neutrons'''. 

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|| 07:22
||Drag the '''Energy''' slider back to its default position.

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|| 07:27
|| Then drag the '''Protons''' and '''Neutrons''' sliders towards '''20'''.

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|| 07:32
||Size of the nucleus becomes small.

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|| 07:35
|| Observe the angles of deflection of '''alpha''' particles.

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|| 07:39
||Angle of deflection decreases with the decrease in protons and neutrons number.

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|| 07:45
|| Here atom is stable as n /p ratio is 1.

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|| 07:50
|| Observe that '''alpha''' particles far from the nucleus have almost no detectable deflection.

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|| 07:57
||While the '''alpha''' particles that are close to the nucleus are deflected.

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|| 08:02
|| As an assignment, 

Try various combinations of protons and neutrons and check the deflections.

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|| 08:10
||Give an explanation for the change in the behaviour of the '''alpha''' particles. 

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|| 08:16
|| Let us summarise.

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|| 08:19
|| In this tutorial, we have demonstrated how to use '''Rutherford Scattering''',''' PhET simulation'''.

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|| 08:28
|| Using this '''simulation''', we have learnt: about '''Plum pudding''' and '''Rutherford''' atomic models,
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|| 08:37
||to visualize the Rutherford gold foil experiment,

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|| 08:41
||about behavior of '''alpha''' particles,

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|| 08:45
||to identify the factors that affect the deflection of '''alpha''' particles.

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|| 08:51
|| The video at the following link summarizes the '''Spoken Tutorial''' project. Please download and watch it.

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|| 09:00
|| The '''Spoken Tutorial Project '''team conducts workshops using spoken tutorials and gives certificates on passing online tests.

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|| 09:09
|| For more details, please write to us.

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|| 09:13
|| Please post your timed queries on this forum.

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|| 09:17
|| This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.

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|| 09:25
|| Spoken Tutorial Project is funded by '''NMEICT, MHRD,''' Government of India.

More information on this mission is available at this link.

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|| 09:38
|| This is Meenal Ghoderao from IIT Bombay.

Thank you for joining.
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