21 Electromagnetic Induction Induction Experimental Magnetic Flux Units

21 Electromagnetic Induction

Induction Experimental

Magnetic Flux Units: Weber (Wb) 1 Wb = 1 T. m 2

Faraday’s Law of Induction The magnitude of the induced emf in a circuit equals the absolute value of the time rate of change of the magnetic flux through the circuit: for 1 turn or for N turns

Generator

Lenz’s Law: Against the change The direction of the any magnetically induced current or emf is such as to oppose the direction of the phenomenon causing it.

Lenz’s Law: Example

Motional Electromotive Force I ? “-”sign: Lenz’s Law Recall Lorentz force on the moving part

Eddy’s Currents

Application: Damping

Application: Speedometer

Application: Hybrid Generator Brake

Mutual Inductance Similarly, Define mutual inductance, M,

Self-Inductance Unit 1 V. s/A = 1 Henry (H) Examples: Solenoid and Toroid

Transformers For an ideal transformer

Transformer & Eddy Current

Magnetic Field Energy per unit volume (using solenoid)

R-L Circuit time t = L/R, time constant

L-C Circuit

Summary: Electromagnetic Induction & Faraday’s Law

Summary: Lenz’s Law

Summary: Motional EMF

Summary: Eddy’s Currents

Summary: Inductance

Summary: Transformers

Summary: Magnetic Energy

Summary: R-L & R-C Circuits

Homework Ch 21: 1, 4, 12, 16, 21, 25, 27, 32, 40, 45, 52.

P 9 -Faraday’s Law

P 16&17 Lenz’s law

P 21&25 -Motional emf

P 27 -Mutual Inductance

P 32 -Self-Inductance

P 40 -Transformer

P 45 -Magnetic Energy

Voltmeter Construction d’ V’ If the V-meter required for maximum V’ (full scale) then

Ammeter Construction d’ Ig