Lab 5: Faraday’s Electromagnetic Induction Lab
Name:
Purpose:
To manipulate simulated magnets, compasses, and coils to see how magnetic fields interact with
electric currents
Apparatus:
Computer
PhET sim, “Faraday’s Electromagnetic Lab”
(https://phet.colorado.edu/sims/cheerpj/faraday/latest/faraday.html?simulation=faraday)
Discussion:
When Hans Christian Ørsted discovered that electricity could be used to produce magnetism, the
scientific community anticipated that it wouldn’t be long before someone would discover how
magnetism could be used to produce electricity. But more than ten years would pass before
Michael Faraday solved the puzzle.
The application of engineering to electromagnetism led to motors and generators. Nearly any
electrical device that produces motion uses a motor. Any device that is plugged into a wall outlet
draws power from a generator. Our reliance on applications of electromagnetism is never more
apparent than during a power outage.
The interactions between electricity and magnetism are not always easy to grasp. In this activity,
you will manipulate elements in a simulated laboratory and get visual feedback.
Procedure:
PART A: ELECTROMAGNET
Step 1: Run the PhET sim, “Faraday’s Electromagnetic Lab.” Maximize the window. Click the
onscreen Electromagnet tab. Arrange the on-screen elements so that the top of the battery is
along the second or third row of the compass grid. Notice that the magnetic field around the coil
is very similar to the magnetic field around the bar magnet.
Step 2: There is no “Strength %” slider on the control panel.
a. How can you change the strength of the electromagnet?
You can change the strength of the electromagnet in the simulation by adjusting the number
of loops in the coils or by adjusting the battery voltage.
1
, b. In real life, is it easier to change the strength of a bar magnet or an electromagnet?
It is easier to adjust the strength of an electromagnet in real life because its strength depends
on the current flowing through the coil, which you can vary. A bar magnet requires you to
change the physical properties such as composition or magnetization.
Step 3: How can you reverse the polarity of the electromagnet?
You can reverse the polarity by reversing the direction of the current flow, switching the
battery connections. To reverse the polarity of the electromagnet in the lab, you can
simply click on the electromagnet itself in the simulation. Clicking on it will toggle the
direction of the current flow which reverses the polarity.
Step 4: In the control panel, switch the Current Source from the battery (DC: direct current) to
an oscillator (AC: alternating current). If necessary, move the electromagnet so that you can see
the entire oscillator.
a. What does the vertical slider on the AC source do?
It adjusts the amplitude (strength) of the alternating current. It changes the maximum value
of the current flowing through the electromagnet.
b. What does the horizontal slider on the AC source do?
The horizontal slider adjusts the frequency (speed of oscillation) of the alternating
current. When you move this slider it changes how quickly the current alternates between
positive and negative values.
Step 5: What should the sliders be set to in order to create a “dance party” display? Can you
make the dance party even more annoying using the Options menu? Describe.
To make a “dance party” display, you can adjust the sliders to high/maximum value. By
adjusting the vertical slider, it will show larger movements of the compass needle and a dynamic
display. By adjusting the horizontal slider, it controls the speed of the dance party effect. Using
the “options” menu, you can click on the “show field lines” option and it will become more
stimulating. You can also have the loops at the highest level it allows – 4.
PART B: PICKUP COIL
2
Name:
Purpose:
To manipulate simulated magnets, compasses, and coils to see how magnetic fields interact with
electric currents
Apparatus:
Computer
PhET sim, “Faraday’s Electromagnetic Lab”
(https://phet.colorado.edu/sims/cheerpj/faraday/latest/faraday.html?simulation=faraday)
Discussion:
When Hans Christian Ørsted discovered that electricity could be used to produce magnetism, the
scientific community anticipated that it wouldn’t be long before someone would discover how
magnetism could be used to produce electricity. But more than ten years would pass before
Michael Faraday solved the puzzle.
The application of engineering to electromagnetism led to motors and generators. Nearly any
electrical device that produces motion uses a motor. Any device that is plugged into a wall outlet
draws power from a generator. Our reliance on applications of electromagnetism is never more
apparent than during a power outage.
The interactions between electricity and magnetism are not always easy to grasp. In this activity,
you will manipulate elements in a simulated laboratory and get visual feedback.
Procedure:
PART A: ELECTROMAGNET
Step 1: Run the PhET sim, “Faraday’s Electromagnetic Lab.” Maximize the window. Click the
onscreen Electromagnet tab. Arrange the on-screen elements so that the top of the battery is
along the second or third row of the compass grid. Notice that the magnetic field around the coil
is very similar to the magnetic field around the bar magnet.
Step 2: There is no “Strength %” slider on the control panel.
a. How can you change the strength of the electromagnet?
You can change the strength of the electromagnet in the simulation by adjusting the number
of loops in the coils or by adjusting the battery voltage.
1
, b. In real life, is it easier to change the strength of a bar magnet or an electromagnet?
It is easier to adjust the strength of an electromagnet in real life because its strength depends
on the current flowing through the coil, which you can vary. A bar magnet requires you to
change the physical properties such as composition or magnetization.
Step 3: How can you reverse the polarity of the electromagnet?
You can reverse the polarity by reversing the direction of the current flow, switching the
battery connections. To reverse the polarity of the electromagnet in the lab, you can
simply click on the electromagnet itself in the simulation. Clicking on it will toggle the
direction of the current flow which reverses the polarity.
Step 4: In the control panel, switch the Current Source from the battery (DC: direct current) to
an oscillator (AC: alternating current). If necessary, move the electromagnet so that you can see
the entire oscillator.
a. What does the vertical slider on the AC source do?
It adjusts the amplitude (strength) of the alternating current. It changes the maximum value
of the current flowing through the electromagnet.
b. What does the horizontal slider on the AC source do?
The horizontal slider adjusts the frequency (speed of oscillation) of the alternating
current. When you move this slider it changes how quickly the current alternates between
positive and negative values.
Step 5: What should the sliders be set to in order to create a “dance party” display? Can you
make the dance party even more annoying using the Options menu? Describe.
To make a “dance party” display, you can adjust the sliders to high/maximum value. By
adjusting the vertical slider, it will show larger movements of the compass needle and a dynamic
display. By adjusting the horizontal slider, it controls the speed of the dance party effect. Using
the “options” menu, you can click on the “show field lines” option and it will become more
stimulating. You can also have the loops at the highest level it allows – 4.
PART B: PICKUP COIL
2
