Homopolar motor experiment

SAFETY NOTE:
Neodymium magnets are extremely strong and MUST BE KEPT OUT OF REACH OF SMALL CHILDREN! Do not give them to any child who might put them in their mouth, they are dangerous if swallowed and must be surgically removed!

 

For more about neodymium magnets safety and precautions go here Additionally neodymium magnets can interfere with electronic devices so please keep them away from phones!
Also please note that these motors do heat up. See our TIPS section for safety precautions.

 

TIPS & PRECAUTIONS:
• MONITOR THESE FOR HEAT! Some of the motors that got going really fast heated up quite quickly. If you notice a battery getting usually warm stop the project, let it cool down and remove the magnets. I recommend against reusing a battery that got overheated. Instead replace it with a fresh battery. One educator warned me about a defective battery that peeled open during this experiment. Please monitor the motors closely as they spin.
• Remove the magnets immediately after running your motor. They will drain your motor if kept attached.
When the electrical circuit is completed you will hear a very low buzz.

 

TROUBLESHOOTING
• If the motor does not work try turning your magnets upside down and reversing the polarity. I found this did the trick most of the time.
• The batteries burn out quickly! If turning the magnets upside down doesn’t work, try replacing your battery with a new one.
• Make sure that the bottom section of wire encircles the magnets. If it doesn’t your motor will not work.
• Be sure your wire is free to move around the battery and magnets. If it’s too close to the battery or magnet it will get stuck and be motionless.
• The motors will need to be fine tuned by hand by you!

 

What’s Going On?
The copper wire connects the positive battery terminal to the magnet at the negative battery terminal, completing the circuit. the a current of electrons will flow through the wire.
Due to the close nest of the magnet at the bottom of the battery, this current actually flows in the presence of a magnetic field. When current flows in a magnetic field, it’ll experience a force — the Lorentz force — that acts perpendicular to both the current’s direction and the direction of the magnetic field.
This force causes the wire to spin in a circle as you can.

 

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