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Build a Faraday Motor with Your Students!

Posted on January 11, 2012 by Dr. Joel Bryan There have been 6 comment(s)

Demonstrate Magnetic Fields, Electric Current, and Basic Principles of the Motor.

In 1820, Danish physicist/chemist Hans Christian Ørsted (Oersted) noticed that when current from his Voltaic pile was switched on and off, a compass needle placed near the wire deflected from true magnetic north. Within a few months of careful study, he deduced that a magnetic field circles a current-bearing wire.

You can learn more about this discovery. See magnet.fsu.edu...

It was not long before scientists and inventors found practical applications of this discovery. In 1821, English physicist/chemist Michael Faraday made brilliant use of two fundamental principles: 1) magnetic fields circle current-bearing wire, and 2) magnetic fields interact with other magnetic fields. He found that the magnetic fields around a permanent magnet and a current-bearing wire could be made to interact and cause motion. This was essentially the first electric motor, and modern motors still operate on this same principle.

Faraday used wire, a battery, a permanent magnet, and a dish of mercury to make his first motor. When current flowed through his circuit, the magnetic field induced around the wire that hung free in the mercury interacted with the magnetic field around a permanent magnet placed within the mercury. This interaction caused the free wire to rotate around the permanent magnetic whenever current flowed through the circuit. You can view a simulation of this early motor at magnet.fsu.edu.

It is fairly simple to construct a working motor similar to Faraday’s original motor that will amaze your students. Due to safety concerns, salt water is substituted for mercury.

Materials: plastic 2L bottles, connecting wires, modern Voltaic pile (i.e., 9V battery), neodymium magnets, salt water, tape, modeling clay, stiff copper wire, aluminum foil, 2 small paper clips, plastic straw, switch (optional)

Construction: Cut one 2L bottle approximately 4 in tall. Place some modeling clay in the bottom of the bottle. Place a stack of neodymium magnets in the tub. Standard steel bar magnets are likely not strong enough. Fill with salt water. Tape the straw to the top of the second 2L bottle. Place stiff copper wire through the straw and attach the paper clips to a hook bent on the end of the wire. The paper clips will serve as a swivel and allow free movement of the hanging stiff cooper wire around the stack of magnets. Connect the other end of the top wire to one terminal of the 9V battery. Connect the other terminal of the 9V battery to the switch. Connect the switch to a folded over piece of aluminum foil. Place the other end of the aluminum foil in the salt water. Connect the other stiff copper wire to the swivel so that it rests in the salt water near the magnet stack. Close the switch and observe the copper wire. Reverse the battery terminals and notice any change in the motion. Turn the stack of magnets over and notice any change in the motion.

faraday motor

Note: Thank you to Dr. Joel Bryan of Ball State University in Muncie, IN for authoring this article and video.

Build your own Motor!

Listed below are the items we sell that will help you construct your motor. In addition to these items you will need 2 plastic 2L bottles, salt water, tape, aluminum foil, 2 small paper clips, and a plastic straw.

Homopolar Motor Kit

Homopolar Motor Kit

Product # P8-8350

$19.00

Includes 10 1/8" thick Neodymium magnets that are ideal for building your Faraday motor and includes copper wire too!
Alligator Leads (Pack of 10)

Alligator Leads (Pack of 10)

Product # P4-3000

$4.50

Pack of 10 Alligator Leads contains 5 red and 5 black leads. You will need 3 of these to complete your circuit.
9 Volt Battery

9 Volt Battery

Product # AR-1000

$1.75

Modern Voltaic pile i.e., Long Lasting 9 volt battery for all your Faraday motor needs.
Knife Switch, Single Pole, Single Throw

Knife Switch, Single Pole, Single Throw

Product # P6-7105

$1.95

Single pole single throw knife switch mounted on a bakelite base with screw holes for mounting.

Modeling Clay

Modeling Clay

Product # PX-2059

$5.00

This clay makes a great base for the Neodymium magnets and includes enough for multiple motors. Comes in a box of 4 different intense colors (red blue green yellow).

This post was posted in CoolStuff Newsletters, Electricity, Magnetism and was tagged with magnetism, faraday motor, voltaic, electric motor


6 Responses to Build a Faraday Motor with Your Students!

  • The demo of the Michael Faraday motor was very interesting and I think it would catch the attention of my physics students. I may well try this one.

    Thanx.

    Posted on January 11, 2012 at 5:54 pm

  • I really liked this experiment.

    Posted on January 12, 2012 at 2:35 pm

  • Thanks for sharing your demo!
    Michael Faraday was a rock star of science. (He had wild hair too- which seems to be a prerequisite for success as a scientist)

    Was electrolysis happening in the brine bath when the motor was running?

    Posted on January 26, 2012 at 7:52 pm

  • I just invented this demonstration in my head, now I check and you already did it. Great job, it works perfectly well; saved me the trouble shooting!

    Posted on September 21, 2013 at 3:39 am

  • georgy says:

    Could u please say the current produced here(AC/DC etc...)

    Posted on June 24, 2014 at 12:42 pm

  • Your current will vary with materials and resistance. This will be direct current.

    Posted on July 18, 2014 at 7:53 am

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