Electromagnetic Induction Or Suduction is all about Induction

Faraday’s and Henry’s Discovery • A changing magnetic field induces a voltage difference. • Also induces a current if inside a conductor • Induced voltage difference is called electromotive force to distinguish it from battery voltage • EMF is directly related to speed of change in magnetic field and number of loops intercepting changing magnetic field (Faraday’s Law e = D B L v)

Lenz’ Law • If a current is induced by a changing magnetic field it will create a second current and a second magnetic field that oppose the original change. • Magnitude of back current and magnetic field directly proportional to speed of change. • Result of conservation of energy • Examples: – Magnet being plunged into coil – Magnet and conducting tube – Burning out a saws motor by stopping blade – Moving magnet and loop problems

The Electric Generator • Device which changes kinetic or mechanical energy into electrical energy • Works by some outside source moving wires inside of magnetic field • Has same parts as motor • Induced voltage is greatest when wires are moving perpendicular to magnetic field • Generates AC or pulsed DC • Fuels vs. Energy transformation

Other Uses of EM Induction • Magnetic identification strips on ATM cards • Smart Lights • Retail Metal detectors • Airport metal detectors • Theramin • Speakers and microphones • Rail guns and mag lev trains