Homopolar Motor

1. Homopolar Motor Materials: AA battery; neodymium magnet; shaped bare copper wire What you do: Assemble so current flows through wire in magnetic field. What students see: Wire spins with no visible gears or motor housing. Question: Where are the motor's 'moving parts'? 2. Simple Coil Motor Materials: Battery; magnet; enamel wire coil; paper-clip supports What you do: Energize balanced coil above magnet. What students see: Coil spins repeatedly. Question: What has to change every half-turn to keep it spinning? 3. Magnet Through Coil Generates Voltage Materials: Coil of wire; strong magnet; sensitive meter/LED What you do: Move magnet into/out of coil at different speeds. What students see: Meter deflects only while magnet is moving. Question: Why is there no signal when the magnet sits still?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: Where are the motor's 'moving parts'? Question: What has to change every half-turn to keep it spinning? Question: Why is there no signal when the magnet sits still?