Demos to Prepare:
The Big Magnet.
The Big Coil..
The Western Telegraph.
Here is a summary of Flemming's rules. For a complete discussion with diagrams, please visit the awesome King of Physics website.
Magnetic Field Around a Conductor:
In a current carrying conductor, the lines of force are circles
perpendicular to the conductor.
Left Hand Rule for a Field Around a Wire:
For Wires: Mentally grasp the wire with the left hand with thumb pointing
in the direction of the electron flow (- to +) and the fingers
will show the direction of the magnetic field (N to S).
Magnetic Field Around a Coil:
For Coils: Mentally grasp the coil with the left hand with fingers in the direction
of the electron flow and the thumb will point to the N pole.
Coils and Solenoids:
The strength of an electromagnet is proportional to the number of ampere•turns.
An iron core concentrates the field.
Powerful Electromagnets save our hero. Video:
Enormous Magnets, Nuclear Particle Detector
Superconducting Magnet in Particle Detector
Super Conductivity in Action, Video:
Solenoids Have Many Uses
The Electric Solenoid releases the Geese of Boomeria at 0500. Video:
The Lock-in Relay prevents the alarm from being stopped. Video:
The Sneak Alarm Uses a Lock-In Relay
Combat Information Center Lock In Relay Up Close
Main Machinery Space, Boomeria, With Relays Galore
The Electric Bell
The Dynamic Microphone
Sound waves vibrate the diaphragm. This moves the coil in the magnetic field. Electricity is generated in the same pattern as the sound waves.
The Electromagnetic Field interacts with the Permanent Magnet Field. The vibrations ---> Sound Waves.
Click to see the Compressions & Rerefactions generated:
Michael Faraday in the "Cockpit" doing Demos