Apps-On-Physics/C3/Magnetism-and-Electromagnetism/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to the Spoken Tutorial on Magnetism and Electromagnetism. |
| 00;07 | At the end of this tutorial you will be able to, |
| 00:11 | Draw magnetic field lines for a bar magnet. |
| 00:15 | Verify right hand thumb rule. |
| 00:18 | Verify Fleming's left hand and right hand rules. |
| 00:23 | Simulate the working of a generator. |
| 00:26 | Here I am using,
Ubuntu Linux OS version 16.04 |
| 00:32 | Firefox web browser version 62.0.3 |
| 00:38 | To follow this tutorial, learner should be familiar with Apps on Physics. |
| 00:43 | For the pre-requisites tutorials please visit this site. |
| 00:49 | In this tutorial we will use, Magnetic Field of a Bar Magnet |
| 00:56 | Magnetic Field of a Straight Current-Carrying Wire |
| 01:00 | Lorentz Force and Generator Apps. |
| 01:04 | I have already downloaded Apps on Physics to my Downloads folder. |
| 01:09 | Right click on magneticfieldbar_en.htm file. |
| 01:15 | Select Open With Firefox web Browser option. |
| 01:19 | Magnetic field bar App opens. |
| 01:22 | The App opens showing a magnet and a magnetic needle. |
| 01:28 | On the green panel there are two buttons.
Clear field lines and Turn magnet. |
| 01:35 | Poles of a bar magnet and compass needle are represented by the following colors. |
| 01:41 | Red for north pole and green for south pole. |
| 01:46 | Click on Turn magnet button. |
| 01:49 | Observe that both bar magnet and magnetic needle change their direction. |
| 01:55 | Let us draw the magnetic field lines.
Place the cursor on the magnetic needle. |
| 02:02 | Click on the magnetic needle and move the needle up and down to draw the magnetic lines. |
| 02:09 | Continue to draw the lines as shown here. |
| 02:13 | Click on the Clear field lines button. |
| 02:17 | Click on Turn magnet button. |
| 02:20 | Again draw the magnetic lines around the magnet. |
| 02:25 | When we turn the magnet, the lines of force change the direction. |
| 02:30 | The direction of magnetic field outside the bar magnet is from north to south.
It is shown by the arrows. |
| 02:39 | Magnetic field is strongest inside the bar magnet. |
| 02:44 | Outside the bar magnet it is strongest near the poles. |
| 02:49 | What is the direction of magnetic field inside the bar magnet? |
| 02:55 | Next we will move on to Magnetic Field Line in a Current Carrying Wire App. |
| 03:00 | Right click on magneticfieldwire_en.htm file. |
| 03:06 | Select Open with Firefox Web browser option. |
| 03:10 | The App opens showing magnetic field lines around a current carrying wire. |
| 03:16 | On the right side of the screen we have a Reverse current button. |
| 03:22 | The red arrow indicates the direction of the current.
Note that the direction of current is opposite to that of electrons. |
| 03:33 | The signs at the end of the wire symbolizes the terminals of the connected battery. |
| 03:40 | The concentric circles are the magnetic field around the current carrying wire. |
| 03:46 | Let us find the direction of magnetic field using right hand thumb rule. |
| 03:53 | Observe the picture and put your right hand as follows. |
| 03:58 | Put your right hand thumb in the direction of the current. |
| 04:03 | Now curl your fingers inside. |
| 04:07 | Fingers gives you the direction of magnetic field. |
| 04:12 | As an assignment,
Reverse the current flow and determine the magnetic field. |
| 04:19 | Let us move on to the next App, Lorentz Force. |
| 04:24 | Follow the same steps as we used for previous App to open htm file. |
| 04:31 | Interface shows a horseshoe magnet through which a conducting wire is passed. |
| 04:37 | The blue arrows shows the direction of the magnetic field. |
| 04:42 | On the green panel we have the following buttons.
On/Off , Reverse current and Turn magnet. |
| 04:51 | When the circuit is open, the wire is shown in black colour. |
| 04:56 | Click on the On/Off button to complete the circuit. |
| 05:01 | Notice that the wire is in conduction mode. |
| 05:06 | This is indicated by the red coloured wire. |
| 05:10 | At the bottom, there are three check-boxes.
These are Current direction, Magnetic field and Lorentz force. |
| 05:20 | The black arrow pointing towards right is the Lorentz force. |
| 05:26 | Lorentz force is always perpendicular to the magnetic field. |
| 05:31 | To change the direction of magnetic field, click on the Turn magnet button. |
| 05:38 | Let us verify the direction of Lorentz force using Fleming’s left-hand rule. |
| 05:45 | Press F5 key on the keyboard to restart the App. |
| 05:50 | First uncheck the Lorentz force check-box. |
| 05:54 | Click on On/Off button. |
| 05:57 | Now keep your fingers of the left hand as suggested here. |
| 06:03 | Index finger pointing in the direction of magnetic field. Middle finger pointing in the direction of current. |
| 06:13 | Thumb shows the direction of Lorentz force. |
| 06:17 | Here the direction of Force is towards the right-side.
This is Fleming’s left-hand rule. |
| 06:25 | Let us verify our answer by checking the Lorentz force check-box. |
| 06:31 | Observe that the direction is same as shown in the App. |
| 06:36 | As an assignment
Reverse the current flow. |
| 06:40 | Determine the direction of lorentz force using Fleming’s left hand rule. |
| 06:47 | Now let us open the Generator App. |
| 06:51 | I will open the App as before. |
| 06:55 | The App shows a generator. |
| 06:58 | An electrical generator converts mechanical energy into electrical energy. |
| 07:05 | The App opens showing a horseshoe magnet. |
| 07:09 | A rectangular current carrying coil is inserted between the poles of the magnet. |
| 07:15 | On the green panel, we can change the rotations per minute using the slider. |
| 07:22 | By default the rectangular coil rotates 6 rotations per minute. |
| 07:28 | We can change the rotation of the coil to a maximum of 12 rotations per minute. |
| 07:35 | Increase the rotation to 12 rotations per minute. |
| 07:40 | In the graph we can see two complete cycles in one minute. |
| 07:46 | Here the frequency of the maximum output voltage is doubled. |
| 07:52 | The rectangular coil is connected to the voltage source through the slip rings. |
| 07:58 | Observe that the rectangular coil is rotating about an axis.
This coil is perpendicular to the magnetic field. |
| 08:09 | Here rotation of the rectangular coil is a source of mechanical energy. |
| 08:16 | Due to the rotation of the coil, current is induced into the wire. |
| 08:22 | The red arrow represents the direction of the induced current. |
| 08:27 | In the green panel we can choose an AC generator or DC generator. |
| 08:34 | By default Without commutator an AC generator is selected. |
| 08:40 | Select With commutator radio button. |
| 08:44 | Commutator is a device for reversing the direction of flow of current. |
| 08:50 | This device ensures that the current flows only in direct current mode. |
| 08:57 | Hence With Commutator means, the generator is a DC generator. |
| 09:03 | On the top of the circuit, voltage v/s time graph is plotted. |
| 09:09 | This is the graph of a DC generator. |
| 09:13 | In the graph, moving blue point indicates the change in voltage. |
| 09:19 | Change direction button changes the direction of the rectangular coil. |
| 09:25 | Click on the Change direction button. |
| 09:28 | Observe the change in the direction of rectangular coil.
Also notice the change in the graph. |
| 09:37 | Press F5 key on the keyboard to restart the App. |
| 09:42 | We can find the direction of induced current using Fleming’s right-hand rule. |
| 09:49 | This rule is same as Fleming’s left-hand rule. |
| 09:53 | Click on the Pause button. |
| 09:56 | Now arrange fingers of your right hand as shown in the figure. |
| 10:01 | We can determine the direction of magnetic field using Fleming's right hand rule. |
| 10:07 | There are three check-boxes at the bottom of the green panel. |
| 10:12 | Direction of movement, Magnetic field and Induced current. |
| 10:18 | Uncheck the Magnetic field check-box.
Notice that the magnetic field lines disappear. |
| 10:27 | In the similar way we can uncheck the remaining check-boxes if not required. |
| 10:33 | Press F5 key on the keyboard to restart the App. |
| 10:38 | AC generator is an alternating current generator. |
| 10:43 | So, here the graph shows positive as well as negative voltages. |
| 10:49 | As an assignment,
Change the rotations per minute to 0, 3.0, 6.0 and 9.0 |
| 10:57 | Note the changes in the movement of the coil and graph.
Explain the reason for the changes. |
| 11:06 | Let us summarise |
| 11:08 | Using these Apps we have,
Drawn magnetic field lines of a bar magnet. |
| 11:15 | Verified right hand thumb rule. |
| 11:18 | Verified Fleming's left hand and right hand rules. |
| 11:23 | Simulated the working of a generator. |
| 11:28 | These Apps were created by Walter Fendt and his team. |
| 11:33 | The video at the following link summarises the Spoken Tutorial project.
Please download and watch it. |
| 11:41 | The Spoken Tutorial Projectteam, conducts workshops and gives certificates.
For more details, please write to us. |
| 11:51 | Please post your timed queries in this forum. |
| 11:55 | The Spoken Tutorial Project is funded by MHRD, Government of India. |
| 12:01 | This is Himanshi Karwanje from IIT-Bombay.
Thank you for joining. |
