PhET/C3/Faradays-Electromagnetic-Lab/English-timed
From Script | Spoken-Tutorial
| 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 |
