Foundations of Physical Science Workshop: Electric Motor

Electric Motor CPO Science

Key Questions  How are electricity and magnetism related?  How does an electric motor work?

Overview

Fun with Magnets  Take your motor completely apart to expose the little ceramic magnets that are in the rotor pockets  What “stupid magnet tricks” can you come up with?  Compare force of attraction with force of repulsion

Fun with Magnets

How does a motor work?

Electromagnets  Coil of wire wrapped around a steel pin  You can reverse polarity by switching direction of electricity

Electromagnets

Switching electromagnet polarity  Mechanism that makes electric current switch direction is called a commutator  Clear = north  Black = south

Switching electromagnet polarity

Build a 4-pole electric motor

Design other motors  Using other colored disks, decide how to build a working motor  Save the green disk for last – it’s a bit tricky!  Use a photogate to measure frequency, and from that calculate the speed in rev per sec (frequency divided by # black areas)  Who can build the fastest motor?