Post on 04-Jan-2016
description
Electromagnetic InductionElectromagnetic Induction Motional Electromagnetic Induction
Use a magnetic field to create a current• emf (electromotive force) ~ potential
difference• Where does the energy come from? → work !
04/20/2304/20/23 APHY101APHY101 11
Electromagnetic InductionElectromagnetic Induction Induction: a coil and a magnet
The amount of induced emf depends on• 1. Strength of the magnetic field• 2. Relative speed of the coil and magnet• 3. Area of the loops• 4. Number of loops
More work is required to move the magnet through a coil with many loops.
• Why?
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Electromagnetic InductionElectromagnetic Induction Electric guitars
The string oscillates above a permanent magnet and coil
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Electromagnetic InductionElectromagnetic Induction Magnetic flux
The amount of a magnetic field that passes through a surface: ΦB = BA cosθ
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Electromagnetic InductionElectromagnetic Induction Faraday’s Law
The emf is proportional to the number of loops times the rate of change of the magnetic field in the loops
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Electromagnetic InductionElectromagnetic Induction Generators
Mechanical energy input with electrical energy output
• Opposite of electric motors
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Electromagnetic InductionElectromagnetic Induction Transformers
Used to increase or decrease an alternating voltage Primary and secondary windings
• Step-up or step-down• The iron core transfers the magnetic field
from one coil to the other
04/20/2304/20/23 APHY101APHY101 77
Electromagnetic InductionElectromagnetic Induction Transformers
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Electromagnetic InductionElectromagnetic Induction Transformers
Power pole
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