PhET-Simulations-for-Physics/C3/Faraday's-Electromagnetic-Lab/English-timed

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Time Narration
00:01 Welcome to this spoken tutorial on Faraday's Electromagnetic Lab.
00:06 In this tutorial, we will demonstrate,Faraday's Electromagnetic Lab PhET simulation.
00:14 Here I am using: Ubuntu Linux OS version 14.04
00:20 Java version 1.8.0
00:24 Firefox web browser version 61.0.1
00:29 To follow this tutorial, Learner should be familiar with topics in high school Physics.
00:36 Using this simulation we will be able to, Predict the change in magnetic field as the magnet moves
00:44 Study the deflections of compass with respect to the magnetic field
00:49 Compare the change in voltage with an induced EMF
00:52 Explain the cause of electromagnetic induction
00:57 Explain the working of a transformer
01:00 Show how a generator works
01:03 For more information please see the additional material provided along with this tutorial.
01:09 Use the given link to download the simulation.
01:13 I have already downloaded Faraday's Electromagnetic Lab simulation to my Downloads folder.
01:20 To run this simulation, open the terminal.
01:23 At the prompt type cd Downloads and press Enter.
01:29 Now type, java space hyphen jar space faraday_en.jar and press Enter.
01:40 Faraday's Electromagnetic Lab simulation opens.
01:45 Simulation interface has five tabs,Bar Magnet,Pickup Coil

,Electromagnet,Transformer,Generator.

01:58 By default Bar Magnet tab opens.
02:02 On the screen we see, a bar magnet with north and south poles marked and a compass.
02:09 Magnetic lines of force are seen spread across the screen.
02:14 A visual cue Move me or me is also seen.
02:19 This visual cue prompts us to drag the magnet or the compass.
02:24 Let us change the needle spacing and needle size.
02:28 This helps us to view the magnetic lines of force clearly.
02:33 Click on Options menu and select Field Controls.
02:38 Field Controls dialog box opens.
02:42 In the dialog box, we have sliders for Needle spacing and Needle size.
02:49 Drag the Needle spacing slider to 60 and Needle size slider to 50x14(50 by 14).
02:57 You can change the sliders as per your requirement.
03:01 Click on OK button and observe the changes.
03:05 Drag the magnet around the screen.
03:08 Note that, magnetic lines of force align and rearrange as we drag the magnet.
03:14 Now drag the compass around the magnet.
03:17 Note that compass needle aligns according to the magnetic lines of force.
03:23 On the right panel, we have Bar Magnet Strength slider.
03:28 Slider can be set between 0 to 100 percent.
03:34 At 0% strength we do not see any magnetic lines of force.
03:40 As we drag the slider towards 100%, magnetic lines of force are seen clearly.
03:47 Click on Flip Polarity button on the right panel.
03:51 Polarity of the magnet changes.
03:54 Change in polarity changes the direction of lines of force and compass needle.
04:00 Click on See Inside Magnet check box in the right panel.
04:05 Observe the direction of lines of force inside the magnet.
04:09 Click on Show Field Meter check box in the right panel.
04:14 Field meter shows up on the screen.
04:17 Drag the Field meter around the field.
04:20 It displays the changing values of, Magnetic flux density B, x component of B(Bx), y component of B(By) and angle of deflection(Ө).
04:34 Now click on Pickup Coil tab.
04:37 This screen demonstrates Faraday's law of Electromagnetic induction.
04:42 Pickup Coil screen has a magnet and a coil connected to a bulb.
04:48 Pickup Coil panel is added to the right panel.
04:52 The bulb acts as an indicator in the circuit.
04:56 Here we can either drag the magnet towards the coil or coil towards the magnet.
05:03 The most effective way is to drag the magnet towards the coil.
05:08 This is because, moving a magnet induces magnetic field around the coil.
05:14 Let us drag the magnet back and forth through the coil.
05:18 Observe that bulb glows.
05:21 This is due to the induced EMF in the coil.
05:25 This creates changing magnetic field around the coil.
05:29 Now let us increase the number of loops to 3 in the Loops input box.
05:34 Then drag the Loop Area slider to 100%.
05:38 Drag the magnet through the loop.
05:41 Observe the glow in the bulb.
05:44 The intensity of the bulb changes as we drag the magnet.
05:50 As an assignment, Replace the bulb with voltage meter.
05:55 Observe the change in the induced EMF, when Magnet is moved rapidly, Polarity of the magnet is flipped
06:05 Explain your observation.
06:09 Click on Electromagnet tab.
06:12 This screen has an electromagnet with its magnetic lines of force and a compass.
06:18 Electromagnet has a 10 v battery as a source of current.
06:23 This Battery has a voltage slider to control the voltage.
06:28 By default electromagnet has DC Current Source.
06:33 Here DC electromagnet creates a constant magnetic field.
06:38 Click on Show Field Meter check-box.
06:42 Place the field meter on the coil.
06:45 Gradually decrease the voltage of the battery from 10 volt to 1 volt.
06:51 Observe the change in speed of electrons on the coil with change in voltage.
06:57 The speed of electron movement decreases as voltage is reduced from 10 volt to 1 volt.
07:04 Magnetic field disappears at zero voltage.
07:08 Now, the coil is no more an electromagnet.
07:12 Continue to drag the voltage slider to the left side towards 10 volt.
07:17 Polarity of electromagnet has changed.
07:21 This changes direction of magnetic lines of force.
07:25 Notice the change in direction of movement of electrons.
07:29 Now let us switch the DC current source to AC.
07:33 Observe the continuously switching magnetic field and compass needle.
07:38 AC Current Supply is provided with two sliders.
07:42 Drag the horizontal slider to change the frequency of the wave.
07:47 Note that rate of magnetic field switching has increased.
07:51 Drag the vertical slider and check what happens?
07:57 As an assignment, Change the number of loops of the coil and observe the magnetic field(B) values.
08:06 Let us see how a transformer works.
08:09 Click on Transformer tab to open it.
08:13 Transformer screen has, an electromagnet with DC current source as a primary coil a Pickup Coil with Indicator as a secondary coil.
08:23 In the transformer, primary coil induces a current into a secondary coil.
08:29 Right panel has Electromagnet and Pickup Coil boxes.
08:34 Click on Show Compass check-box in Electromagnet box.
08:39 In a transformer, two coils are linked together by an iron core.
08:44 However, in this case we don't have the iron core to link the coils.
08:49 Move the coils close, so that they touch each other.
08:53 At the stationary position there is no change in the flux.
08:57 Hence, bulb does not glow.
09:00 To induce voltage in the secondary coil, magnetic field should vary.
09:05 Drag the voltage slider of the electromagnet back and forth.
09:10 As we drag, notice that bulb glows.
09:14 Also, note the deflections in the compass needle and direction of flow of electrons.
09:20 Next drag the primary coil in and out of the secondary coil.
09:25 Observe the change in flux as we move the coil.
09:29 Now bulb glows brightly.
09:32 From the Electromagnet box, change the DC source to AC source.
09:37 AC current in primary coil produces a changing magnetic field.
09:42 This changing magnetic field induces a voltage in the secondary coil.
09:47 Observe the change in voltage in the bulb with changing magnetic field.
09:52 In the AC current supply, increase the amplitude.
09:56 With the increase in amplitude of the wave, bulb glows brightly.
10:01 Drag the horizontal slider to increase the frequency.
10:05 Notice the fast flickering in the bulb and deflections on compass.
10:10 This is due to change in voltage in the coils.
10:14 Note that there are 4 loops on the primary coil and 2 loops on the secondary coil.
10:20 Now increase the number of loops on secondary coil to 3.
10:24 Reduce the number of loops of primary coil to 1.
10:28 Note the change in voltage of the bulb in the transformer.
10:34 As an assignment, Check what happens when frequency slider of AC Current Supply is moved to 5%?
10:42 Explain your observation.
10:46 Now we will move on to Generator.
10:49 Click on Generator tab to open it.
10:52 This is a simple version of a generator.
10:55 On the right panel, we have Bar Magnet and Pickup Coil boxes.
11:00 Under the Bar magnet box, click on Show Field and Show Field Meter check-boxes.
11:07 Screen has a faucet, paddlewheel with a bar magnet, pickup coil, compass and Field Meter.
11:18 By default the Bar magnet is at 0 RPM (revolutions per minute).
11:23 Drag and place the Field Meter close to the coil.
11:27 Drag the slider to turn on the faucet.
11:30 Observe that the bar magnet starts spinning as water falls on it.
11:35 As the magnet rotates, magnetic lines of force change continuously.
11:40 Notice the change in the values in the Field Meter.
11:44 This results in the production of induced EMF in the coil and bulb glows.
11:50 Now lets increase the rotation of magnet to 100 RPM.
11:55 Drag the faucet slider gradually to maximum.
11:59 Observe the rapidly changing magnetic field with increase in RPM.
12:04 Now bulb glows brightly as the voltage increases.
12:09 Pause the tutorial and do this assignment.
12:13 What changes do you see in the working of the generator, when

1. Number of loops and loop area of the wire are changed.

12:22 2. Bar magnet strength is reduce to 0%?
12:26 Let us summarise.
12:28 In this tutorial we have demonstrated,How to use Faraday's Electromagnetic Lab, PhET simulation.
12:36 Using this simulation we have,Predicted the change in magnetic field as the magnet moves.
12:43 Studied the deflections of compass with respect to the magnetic field.
12:48 Compared change in voltage with induced EMF.
12:52 Explained the cause of electromagnetic induction.
12:56 Explained how a transformer works.
13:00 Shown how a generator works.
13:03 The video at the following link summarizes the Spoken Tutorial project.
13:08 Please download and watch it.
13:10 The Spoken Tutorial Project team:conducts workshops using spoken tutorials and gives certificates on passing online tests.
13:19 For more details, please write to us.
13:23 Please post your timed queries in this forum.
13:36 This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
13:34 Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
13:41 More information on this mission is available at this link.
13:46 This tutorial is contributed by Madhuri Ganapathi and Meenal Ghoderao from IIT-Bombay.
13:52 Thank you for joining

Contributors and Content Editors

Nancyvarkey