Science Buddies: "Ask an Expert"

My daughter has built a homopolar motor for a science fair project. We needs help with one question that we cannot figure out experimenting as we have no measurement devices. Does the size of the neodymium magnets used change the speed of the wire spinning? We are using 12mmx3mm and 18mmx3mm magnets and visually I don't really see a big difference in the wire. Please HELP !!!

Hi hinahassan,

I'm assuming that you're working on the project described here or something similar:

https://www.sciencebuddies.org/science- ... or#summary

The larger magnets probably have a greater magnetic field than the smaller ones. That should result in a higher speed. To measure speed you might try making a video of the motor in action with each magnet size. Use slow motion playback to count wire revolutions for a set time period.

I hope this helps. Please ask again if you have more questions.

A. Norman