Difference between revisions of "PhET/C3/Photoelectric-Effect/English-timed"

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|| In this tutorial we will learn- How to use interactive '''PhET simulation''', '''Photoelectric Effect'''.
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|| In this tutorial, we will learn- how to use interactive '''PhET simulation''', '''Photoelectric Effect'''.
  
 
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|| 00:15
 
|| 00:15
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|| To follow this tutorial, learners should be familiar with topics in high school science.
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|| To follow this tutorial, learners should be familiar with topics in high-school science.
  
 
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|| Here I am using-  
 
|| Here I am using-  
  
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Ubuntu Linux OS version 14.04
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'''Ubuntu Linux OS''' version 14.04,
  
 
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|| 00:28
 
|| 00:28
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||Java version 1.7.0
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||'''Java''' version 1.7.0,
  
 
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|| 00:32
 
|| 00:32
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||Firefox Web Browser version 53.02.2.
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||'''Firefox Web Browser''' version 53.02.2.
  
 
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|| 01:11
 
|| 01:11
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|| Use the given link to download the simulation.
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|| Use the given '''link''' to download the '''simulation'''.
  
 
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|| 01:22
 
|| 01:22
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|| Open the terminal.
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|| Open the '''terminal'''.
  
 
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|| 01:24
 
|| 01:24
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||At the prompt type '''cd Downloads''' and press enter.
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||At the prompt, type: '''cd Downloads''' and press '''Enter'''.
  
 
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|| 01:29
 
|| 01:29
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||Then type, '''java space hyphen jar space photoelectric_en.jar''' and press enter.
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||Then type: '''java space hyphen jar space photoelectric_en.jar''' and press '''Enter'''.
  
 
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|| 01:44
 
|| 01:44
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|| Do not close the terminal, it will kill the process.
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|| Do not close the terminal, it will '''kill''' the process.
  
 
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|| 01:52
 
|| 01:52
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|| This is the interface of '''Photoelectric Effect''' simulation.
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|| This is the '''interface''' of '''Photoelectric Effect''' simulation.
  
 
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|| 01:57
 
|| 01:57
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|| This screen has a menu bar, with menu items, '''File''', '''Options''' and '''Help'''.
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|| This '''screen''' has a menu bar with menu items- '''File''', '''Options''' and '''Help'''.
  
 
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|| 02:19
 
|| 02:19
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|| We can change '''Intensity''' and wavelength by dragging the respective sliders.
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|| We can change '''Intensity''' and wavelength by dragging the respective '''slider'''s.
  
 
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|| 02:33
 
|| 02:33
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|| Photoelectric Effect is carried out inside a vacuum chamber.
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|| '''Photoelectric''' effect is carried out inside a vacuum chamber.
  
 
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|| 02:38
 
|| 02:38
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|| A vacuum chamber consists of - A metal surface and a detector to measure kinetic energy of electrons.
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|| A vacuum chamber consists of a metal surface and a detector to measure kinetic energy of electrons.
  
 
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|| 02:58
 
|| 02:58
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|| A '''Play/Pause''' and '''Step''' buttons are at the bottom of the screen.
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|| A '''Play/Pause''' and '''Step''' buttons are at the bottom of the '''screen'''.
  
 
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|| 03:04
 
|| 03:04
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|| On the right-side of the screen, we can see, a '''Target''' drop down box to choose metals.
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|| On the right side of the screen, we can see a '''Target''' drop down box to choose metals.
  
 
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|| 03:11
 
|| 03:11
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|| By default '''Sodium''' is selected as Target metal.  
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|| By default, '''Sodium''' is selected as '''Target''' metal.  
  
 
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|| 03:16
 
|| 03:16
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|| For accuracy in results let's move the '''Intensity''' slider to '''50%'''.  
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|| For accuracy in results, let's move the '''Intensity''' slider to '''50%'''.  
  
 
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|| 03:23
 
|| 03:23
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|| In '''Options''' menu click on '''Show photons''' option.
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|| In '''Options''' menu, click on '''Show photons''' option.
  
 
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|| 03:34
 
|| 03:34
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|| Uncheck '''Show photons''' option.
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|| Un-check '''Show photons''' option.
  
 
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|| 03:36
 
|| 03:36
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|| By default the wavelength slider is at '''400 nanometer'''.  
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|| By default, the wavelength slider is at '''400 nano-meter'''.  
  
 
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|| 03:58
 
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|| For '''0 V''' (zero voltage) value of current is shown as '''0.071'''.
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|| For '''0 V''' (zero voltage), value of current is shown as '''0.071'''.
  
 
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|| 04:05
 
|| 04:05
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|| Under '''Graphs''' we have the following check boxes -
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|| Under '''Graphs''', we have the following check boxes -
  
 
|-
 
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|| 04:09
 
|| 04:09
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|| '''Current Vs battery voltage'''
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|| '''Current Vs battery voltage''',
  
 
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|| 04:12
 
|| 04:12
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|| '''Current Vs light intensity'''
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|| '''Current Vs light intensity''',
  
 
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|| 05:35
 
|| 05:35
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|| Now click on '''Electron energy Vs light Frequency''' graph check box.
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|| Now, click on '''Electron energy Vs light Frequency''' graph check box.
  
 
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|| 09:05
 
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|| As an assignment, Calculate the Threshold Frequency of '''Platinum'''.
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|| As an assignment, calculate the '''Threshold Frequency''' of '''Platinum'''.
  
 
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|| 09:38
 
|| 09:38
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|| Elements with low Ionization enthalpy values have low work function.
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|| Elements with low ionization enthalpy values have low work function.
  
 
Example: Lithium, Sodium, Potassium, Rubidium, and Caesium.
 
Example: Lithium, Sodium, Potassium, Rubidium, and Caesium.
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|| 10:04
 
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|| Work function for Sodium is 2.31eV.(electron volts)  
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|| Work function for Sodium is 2.31 eV.(electron volts)  
  
 
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|| 10:41
 
|| 10:41
 
|| Drag the wavelength slider to threshold wavelength of sodium.
 
|| Drag the wavelength slider to threshold wavelength of sodium.
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That is '''539 nano-meter'''.
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That is '''539 nanometer'''.
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|| 11:08
 
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|| Observe At '''-0.04 Volts''', no electrons are ejected from sodium.  
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|| Observe, at '''-0.04 Volts''', no electrons are ejected from sodium.  
  
 
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|| 11:16
 
|| 11:16
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|| As an assignment, Calculate the work function for Zinc, Copper and Calcium.
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|| As an assignment, calculate the work function for Zinc, Copper and Calcium.
  
 
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||11:36
 
||11:36
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|| Using this simulation, we have learnt,  About Photoelectric Effect.
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|| Using this simulation, we have learnt about: Photoelectric Effect,
  
 
|-
 
|-
 
|| 11:41
 
|| 11:41
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||  To determine '''Threshold Frequency'''.
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||  to determine '''Threshold Frequency''',
  
 
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|| 11:44
 
|| 11:44
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||  To find '''Stopping Potential''' and '''Work Function''' and
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||  to find '''Stopping Potential''' and '''Work Function''' and
  
 
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|| 11:48
 
|| 11:48
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||  Study the factors affecting current and energy of electrons.
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||  study the factors affecting current and energy of electrons.
  
 
|-
 
|-
 
|| 11:54
 
|| 11:54
−
|| The video at the following link summarizes the Spoken Tutorial project.
+
|| The video at the following link summarizes the '''Spoken Tutorial''' project.
  
 
Please download and watch it.
 
Please download and watch it.
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|-
 
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|| 12:03
 
|| 12:03
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|| The Spoken Tutorial Project team: conducts workshops using spoken tutorials and
+
|| The Spoken Tutorial Project team conducts workshops using spoken tutorials and
−
 
+
 
gives certificates on passing online tests.
 
gives certificates on passing online tests.
  
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|-
 
|-
 
|| 12:31
 
|| 12:31
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|| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
+
|| Spoken Tutorial Project is funded by '''NMEICT, MHRD,''' Government of India.
  
 
More information on this mission is available at this link.
 
More information on this mission is available at this link.

Latest revision as of 19:28, 13 August 2018

Time Narration
00:01 Welcome to this tutorial on Photoelectric Effect, PhET simulation.
00:07 In this tutorial, we will learn- how to use interactive PhET simulation, Photoelectric Effect.
00:15 To follow this tutorial, learners should be familiar with topics in high-school science.
00:22 Here I am using-

Ubuntu Linux OS version 14.04,

00:28 Java version 1.7.0,
00:32 Firefox Web Browser version 53.02.2.
00:38 Using this simulation, students will be able to-

1. Study Photoelectric Effect.

00:44 2. Determine Threshold frequency.
00:47 3. Find Stopping potential and Work function.
00:51 4. Study the factors affecting current and energy of electrons.
00:56 When light of a particular frequency strikes a metal surface, electrons are ejected.
01:04 Ejected electrons are counted by a detector that measures their kinetic energy.
01:11 Use the given link to download the simulation.
01:15 I have already downloaded the Photoelectric Effect simulation to my Downloads folder.
01:22 Open the terminal.
01:24 At the prompt, type: cd Downloads and press Enter.
01:29 Then type: java space hyphen jar space photoelectric_en.jar and press Enter.
01:40 Photoelectric Effect simulation opens.
01:44 Do not close the terminal, it will kill the process.
01:49 Click Cancel to continue.
01:52 This is the interface of Photoelectric Effect simulation.
01:57 This screen has a menu bar with menu items- File, Options and Help.
02:05 Options menu has two options, Show photons and Control photon number instead of intensity.
02:14 Screen has a lamp to shine light on the metal surface.
02:19 We can change Intensity and wavelength by dragging the respective sliders.
02:26 We can also input Intensity and wavelength values in their respective boxes.
02:33 Photoelectric effect is carried out inside a vacuum chamber.
02:38 A vacuum chamber consists of a metal surface and a detector to measure kinetic energy of electrons.
02:48 A battery and a current indicator are connected in the circuit.
02:53 Battery is provided with a Voltage slider.
02:58 A Play/Pause and Step buttons are at the bottom of the screen.
03:04 On the right side of the screen, we can see a Target drop down box to choose metals.
03:11 By default, Sodium is selected as Target metal.
03:16 For accuracy in results, let's move the Intensity slider to 50%.
03:23 In Options menu, click on Show photons option.
03:28 Observe that light is shined in the form of photons.
03:34 Un-check Show photons option.
03:36 By default, the wavelength slider is at 400 nano-meter.
03:42 Electrons are ejected as soon as light falls on Sodium metal surface.
03:48 There is no time lag between incident radiation and electrons emission.
03:54 These electrons flow towards a detector.
03:58 For 0 V (zero voltage), value of current is shown as 0.071.
04:05 Under Graphs, we have the following check boxes -
04:09 Current Vs battery voltage,
04:12 Current Vs light intensity,
04:15 Electron energy Vs light frequency.
04:19 Click on Current vs battery voltage check box.
04:23 We see a graph of current vs battery voltage.
04:29 Notice a red dot on the graph.
04:32 Drag the voltage slider slowly from 0 to 6.00 volts.
04:38 Notice that current remains constant as we increase the voltage.
04:44 This is indicated by the red line.
04:48 As we increase the voltage, speed of photoelectrons increases.
04:53 Let us see how intensity of light affects the current.
04:58 Click on Current vs light intensity check box.
05:03 Drag the Intensity slider upto 90%.
05:08 Notice that current increases linearly with the increase in intensity.
05:14 This is indicated by the green line.
05:18 Increase in intensity of light increases the magnitude of photoelectric current.
05:24 Now Current value is shown as 0.127.
05:30 Drag the Intensity slider back to 50%.
05:35 Now, click on Electron energy Vs light Frequency graph check box.
05:42 Drag the wavelength slider towards UV region.

Observe the graphs.

05:49 Notice that energy increases linearly with the increase in Frequency.
05:55 This is indicated by the blue line.
05:59 Observe the change in current.
06:02 Increase in frequency, increases the energy of photoelectrons.
06:08 As frequency increases, energy transfer from photons to electrons increases.
06:15 This results in increase in the kinetic energy of ejected electrons.
06:21 Now click on a Camera icon.
06:24 A snapshot window opens.
06:27 It gives information about Graphs and Experimental Parameters.
06:33 Using this snapshot, we can compare graphs with different settings.
06:39 Close the snapshot window.
06:42 Now we will discuss how to calculate the Threshold Frequency.
06:48 Each metal has a characteristic minimum frequency to cause photoelectric emission.
06:55 This frequency is, Threshold Frequency, denoted by ʋ0.
07:01 Below the Threshold Frequency, Photoelectric Effect is not observed.
07:07 Drag the wavelength slider towards visible region.
07:12 Observe the wavelength at which electron ejection stops.
07:18 Notice that at 540 nm no more electrons are ejected from Sodium.
07:25 Let's type 539 nm in the wavelength text box and observe.
07:32 At 539 nm electrons start ejecting from sodium metal surface.
07:39 It means that, 539 nm is threshold wavelength for Sodium.
07:45 Here, value of current is 0.00.
07:49 Now let us calculate the threshold frequency value.
07:54 Here wavelength is shown in nano metres(nm).
07:58 I will convert it to metres by multiplying with 10 to the power of -9
08:05 Threshold frequency can be calculated using following formula.
08:10 Threshold frequency of sodium is 0.56 x 10 to the power of 15 </sup>Hz.
08:18 Now let us select Platinum as Target.
08:22 Click on drop down arrow and select Platinum.
08:26 At this wavelength we do not see ejection of photoelectrons.
08:31 Drag the slider to UV region untill electron ejection starts.
08:39 Drag the wavelength slider to lower wavelength region.
08:45 Notice that a large number of electrons with different energies are ejected.
08:52 To view electrons with highest energy, click on Show only highest energy electrons check box.
09:00 Uncheck the box to show electrons with different energies.
09:05 As an assignment, calculate the Threshold Frequency of Platinum.
09:11 We will move on to the calculation of work function and stopping voltage.
09:17 Work function is minimum amount of energy necessary to start photoelectric emission.
09:24 Different metals have different values of work function.
09:29 It is denoted by ϕ0.
09:32 Work function is given by ϕ0= hʋ0.
09:38 Elements with low ionization enthalpy values have low work function.

Example: Lithium, Sodium, Potassium, Rubidium, and Caesium.

09:51 Let us calculate the work function for Sodium.
09:55 Work function is calculated by using following formula.

w0 = hʋ0

10:04 Work function for Sodium is 2.31 eV.(electron volts)
10:10 Similarly work function for Calcium is 2.9 eV (electron volts)
10:17 Stopping Potential- It is a negative voltage required to stop electrons from reaching the other side.
10:26 At Stopping Potential, photoelectric current becomes zero.
10:31 Let's see how to determine the stopping potential for Sodium.
10:37 Change Sodium as target metal.
10:41 Drag the wavelength slider to threshold wavelength of sodium.

That is 539 nano-meter.

10:51 Drag the voltage slider to negative voltage.
10:56 At which voltage, electrons will bounce off from detector?
11:01 At -0.01 V(volts), electrons start to bounce off from detector.
11:08 Observe, at -0.04 Volts, no electrons are ejected from sodium.
11:16 As an assignment, calculate the work function for Zinc, Copper and Calcium.
11:22 Determine the stopping potential for the same metals.
11:27 Let us summarize. In this tutorial we have learnt about,

Photoelectric Effect, PhET simulation.

11:36 Using this simulation, we have learnt about: Photoelectric Effect,
11:41 to determine Threshold Frequency,
11:44 to find Stopping Potential and Work Function and
11:48 study the factors affecting current and energy of electrons.
11:54 The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

12:03 The Spoken Tutorial Project team conducts workshops using spoken tutorials and

gives certificates on passing online tests.

12:13 For more details, please write to us.
12:17 Please post your timed queries on this forum.
12:22 This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
12:31 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

12:43 This is Meenal Ghoderao from IIT Bombay.

Thank you for joining.

Contributors and Content Editors

Madhurig, PoojaMoolya, Sandhya.np14

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