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Revision as of 22:24, 7 May 2021

Visual Cue Narration
Slide Number 1

Title slide

Welcome to this spoken tutorial on Faraday's Electromagnetic Lab.
Slide Number 2

Learning objectives

In this tutorial, we will demonstrate,

Faraday's Electromagnetic Lab PhET simulation.

Slide Number 3

System Requirements

Here I am using-

Ubuntu Linux OS version 14.04

Java version 1.8.0

Firefox web browser version 61.0.1

Slide Number 4

Pre-requisites

To follow this tutorial,

Learner should be familiar with topics in high school Physics.

Slide Number 5

Learning Goals

Using this simulation we will be able to,
  • Predict the change in magnetic field as the magnet moves
  • Study the deflections of compass with respect to the magnetic field
  • Compare the change in voltage with an induced EMF
Slide Number 6

Learning Goals

  • Explain the cause of electromagnetic induction
  • Explain the working of a transformer
  • Show how a generator works
For more information please see the additional material provided along with this tutorial.
Slide Number 7

Link for PhET simulation

http://phet.colorado.edu

Use the given link to download the simulation.

http://phet.colorado.edu

Point to faraday_en.jar. I have already downloaded Faraday's Electromagnetic Lab simulation to my Downloads folder.
To open java file,

Press Ctrl+Alt+T keys.

Type cd Downloads >> press Enter.

To run this simulation, open the terminal.

At the prompt type cd Downloads and press Enter.

Type java -jar faraday_en.jar >> press Enter.

Point to interface.

Now type, java space hyphen jar space faraday_en.jar and press Enter.

Faraday's Electromagnetic Lab simulation opens.

Point to different tabs. Simulation interface has five tabs.

Bar Magnet

Pickup Coil

Electromagnet

Transformer

Generator

Point to the Bar Magnet tab. By default Bar Magnet tab opens.
Point to the bar magnet and compass. On the screen we see,

a bar magnet with north and south poles marked and a compass.

Point to the lines of force. Magnetic lines of force are seen spread across the screen.
Point to the visual cue. A visual cue Move me or me is also seen.

This visual cue prompts us to drag the magnet or the compass.

Cursor on the interface.

Point to magnetic lines of force.

Let us change the needle spacing and needle size.

This helps us to view the magnetic lines of force clearly.

Click on Options menu >> select Field Controls.

Point to the Field Controls dialog box.

Click on Options menu and select Field Controls.

Field Controls dialog box opens.

Point Needle spacing and Needle size sliders. In the dialog box, we have sliders for Needle spacing and Needle size.
Drag the Needle spacing slider to 60 >> Needle size slider to 50x14. Drag the Needle spacing slider to 60 and Needle size slider to 50x14(50 by 14).
Highlight the changes. You can change the sliders as per your requirement.
Click OK button. Click on OK button and observe the changes.
Drag the magnet around the screen. Drag the magnet around the screen.
Point to the magnetic field. Note that, magnetic lines of force align and rearrange as we drag the magnet.
Drag the compass around the magnet.

Point to compass needle.

Now drag the compass around the magnet.

Note that compass needle aligns according to the magnetic lines of force.

Point to the Bar Magnet Strength slider.

Cursor on the slider.

On the right panel, we have Bar Magnet Strength slider.

Slider can be set between 0 to 100 percent.

Drag the slider to 0%. At 0% strength we do not see any magnetic lines of force.
Drag the slider 100%. As we drag the slider towards 100%, magnetic lines of force are seen clearly.
Click on Flip Polarity button. Click on Flip Polarity button on the right panel.
Point to the magnet. Polarity of the magnet changes.
Point to field lines and compass needle. Change in polarity changes the direction of lines of force and compass needle.
Click on See Inside Magnet check box in the right panel.

Point to the lines.

Click on See Inside Magnet check box in the right panel.

Observe the direction of lines of force inside the magnet.

Click on Show Field Meter check box. Click on Show Field Meter check box in the right panel.
Point to field meter. Field meter shows up on the screen.
Drag the Field meter around the field.

Point to the values of B, Bx, By and Ө.

Drag the Field meter around the field.

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).

Click on Pickup Coil tab.

Cursor on the interface.

Now click on Pickup Coil tab.

This screen demonstrates Faraday's law of Electromagnetic induction.

Point to magnet and a coil.

Point to the bulb.

Pickup Coil screen has a magnet and a coil connected to a bulb.

Pickup Coil panel is added to the right panel.

The bulb acts as an indicator in the circuit.

Move and show. Here we can either drag the magnet towards the coil or coil towards the magnet.
Drag the magnet towards the coil. The most effective way is to drag the magnet towards the coil.

This is because, moving a magnet induces magnetic field around the coil.

Drag the magnet back and forth through the coil.

Point to the bulb.

Let us drag the magnet back and forth through the coil.

Observe that bulb glows.

Point to changing magnetic field. This is due to the induced EMF in the coil.

This creates changing magnetic field around the coil.

Click on Loops input box>> increase the number of loops to 3. Now let us increase the number of loops to 3 in the Loops input box.
Drag the Loop Area slider to 100. Then drag the Loop Area slider to 100%.
Drag the magnet through the loop.

Point to the bulb.

Point to the bulb.

Drag the magnet through the loop.

Observe the glow in the bulb.

The intensity of the bulb changes as we drag the magnet.

Slide Number 8

Assignment

As an assignment,

Replace the bulb with voltage meter.

Observe the change in the induced EMF, when

1. Magnet is moved rapidly

2. Polarity of the magnet is flipped

Explain your observation.

Click on Electromagnet tab. Click on Electromagnet tab.
Point to electromagnet, magnetic lines of force and compass. This screen has an electromagnet with its magnetic lines of force and a compass.
Point to 10 v battery.

Point to voltage slider.

Electromagnet has a 10 v battery as a source of current.

This Battery has a voltage slider to control the voltage.

Point to DC Current Source. By default electromagnet has DC Current Source.
Point to magnetic field. Here DC electromagnet creates a constant magnetic field.
Check Show Field Meter check-box.

Place the field meter on the coil.

Click on Show Field Meter check-box.

Place the field meter on the coil.

Drag the voltage slider towards zero.

Point to electrons.

Gradually decrease the voltage of the battery from 10 volt to 1 volt.

Observe the change in speed of electrons on the coil with change in voltage.

Point to electron movement. The speed of electron movement decreases as voltage is reduced from 10 volt to 1 volt.
Point to magnetic field lines. Magnetic field disappears at zero voltage.

Now, the coil is no more an electromagnet.

Drag the slider to left side towards 10 v. Continue to drag the voltage slider to the left side towards 10 volt.
Point to compass needle. Polarity of electromagnet has changed.

This changes direction of magnetic lines of force.

Point to electrons. Notice the change in direction of movement of electrons.
Point to DC and AC.

Click on AC current source.

Now let us switch the DC current source to AC.
Point to field meter and compass needle. Observe the continuously switching magnetic field and compass needle.
Point to two sliders. AC Current Supply is provided with two sliders.
Drag the horizontal slider.

Point to magnetic field lines and meter.

Point to the Amplitude slider.

Drag the horizontal slider to change the frequency of the wave.

Note that rate of magnetic field switching has increased.

Drag the vertical slider and check what happens?

Slide Number 9

Assignment

As an assignment,

Change the number of loops of the coil

and observe the magnetic field(B) values.

Let us see how a transformer works.
Click on Transformer tab. Click on Transformer tab to open it.
Point to Electromagnet.

Point to Pickup Coil.

Transformer screen has,
  • an electromagnet with DC current source as a primary coil
  • a Pickup Coil with Indicator as a secondary coil
Point to both the coils. In the transformer, primary coil induces a current into a secondary coil.
Point to Electromagnet and Pickup Coil boxes. Right panel has Electromagnet and Pickup Coil boxes.
Click on Show Compass check-box. Click on Show Compass check-box in Electromagnet box.
Cursor on interface.

Drag the coils close to each other.

In a transformer, two coils are linked together by an iron core.

However, in this case we don't have the iron core to link the coils.

Move the coils close, so that they touch each other.

Point to area of the loop.

Point to light bulb.

At the stationary position there is no change in the flux.

Hence, bulb does not glow.

Point to the secondary coil. To induce voltage in the secondary coil, magnetic field should vary.
Drag the slider to left side.

Point to light bulb.

Point to compass needle and electrons.

Drag the voltage slider of the electromagnet back and forth.

As we drag, notice that bulb glows.

Also, note the deflections in the compass needle and direction of flow of electrons.

Move primary coil in and out of the secondary coil.

Point to area of loop.

Point to light bulb.

Next drag the primary coil in and out of the secondary coil.

Observe the change in flux as we move the coil.

Now bulb glows brightly.

Point to Electromagnet box.

Click on AC source.

From the Electromagnet box, change the DC source to AC source.
Point to magnetic field lines.

Point to the secondary coil.

AC current in primary coil produces a changing magnetic field.

This changing magnetic field induces a voltage in the secondary coil.

Point to light bulb. Observe the change in voltage in the bulb with changing magnetic field.
Drag the vertical slider of AC current supply.

Point to light bulb.

In the AC current supply, increase the amplitude.

With the increase in amplitude of the wave, bulb glows brightly.

Drag the horizontal slider. Drag the horizontal slider to increase the frequency.
Point to light of light bulb and compass needle. Notice the fast flickering in the bulb and deflections on compass.

This is due to change in voltage in the coils.

Point to coils of primary and secondary coil. Note that there are 4 loops on the primary coil and 2 loops on the secondary coil.
Under Pickup Coil box,

Click on Loops input box >> increase the number of loops to 3.

Under Electromagnet box, Reduce the number of loops to 1.

Now increase the number of loops on secondary coil to 3.

Reduce the number of loops of primary coil to 1.

Point to light bulb. Note the change in voltage of the bulb in the transformer.
Slide Number 10

Assignment

As an assignment,

Check what happens when frequency slider of AC Current Supply is moved to 5%?

Explain your observation.

Point to Generator. Now we will move on to Generator.
Click on Generator tab.

Point to left side of the screen.

Click on Generator tab to open it.

This is a simple version of a generator.

Point to the tools on the right side of the screen. On the right panel, we have Bar Magnet and Pickup Coil boxes.
Click on Show Field >> Show Field Meter check-boxes. Under the Bar magnet box, click on Show Field and Show Field Meter check-boxes.
Point to faucet, paddlewheel with bar magnet, pickup coil, compass and Field Meter. Screen has a faucet, paddlewheel with a bar magnet, pickup coil, compass and Field Meter.
Point to bar magnet. By default the Bar magnet is at 0 RPM (revolutions per minute).
Drag, place Field Meter close to coil. Drag and place the Field Meter close to the coil.
Drag slider at the top of tap. Drag the slider to turn on the faucet.
Point to rotating bar magnet.

Point to changing magnetic lines.

Point to compass.

Observe that the bar magnet starts spinning as water falls on it.

As the magnet rotates, magnetic lines of force change continuously.

Point to Field Meter and compass. Notice the change in the values in the Field Meter.
Point to light bulb. This results in the production of induced EMF in the coil and bulb glows.
Point to RPM value. Now lets increase the rotation of magnet to 100 RPM.
Drag the faucet slider to the extreme right end. Drag the faucet slider gradually to maximum.
Point to magnetic field lines. Observe the rapidly changing magnetic field with increase in RPM.
Point to light bulb. Now bulb glows brightly as the voltage increases.
Pause the tutorial and do this assignment.
Slide Number 11

Assignment

What changes do you see in the working of the generator, when

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

2. Bar magnet strength is reduce to 0%?

Let us summarise.
Slide Number 12

Summary

In this tutorial we have demonstrated,

How to use Faraday's Electromagnetic Lab, PhET simulation.

Slide Number 13

Summary

Using this simulation we have,

Predicted the change in magnetic field as the magnet moves.

Studied the deflections of compass with respect to the magnetic field.

Compared change in voltage with induced EMF.

Slide Number 14

Summary

Explained the cause of electromagnetic induction.

Explained how a transformer works.

Shown how a generator works.

Slide Number 15

About Spoken Tutorial project

The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

Slide Number 16

Spoken Tutorial workshops

The Spoken Tutorial Project team:

conducts workshops using spoken tutorials and

  • gives certificates on passing online tests.

For more details, please write to us.

Slide Number 17

Forum for specific questions:

Do you have questions in THIS Spoken Tutorial?

  • Please visit this site
  • Choose the minute and second where you have the question
  • Explain your question briefly
  • Someone from our team will answer them
Please post your timed queries in this forum.
Slide Number 18

Acknowledgements

This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching.
Slide Number 19

Acknowledgement

Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at

this link.

This tutorial is contributed by Madhuri Ganapathi and Meenal Ghoderao from IIT-Bombay.

Thank you for joining

Contributors and Content Editors

Madhurig

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