Lesson Notes By Weeks and Term v4 - SHS 3
ELECTROMAGNETIC INDUCTION & APPLICATIONS
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ELECTROMAGNETIC INDUCTION & APPLICATIONS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Physics
Class: SHS 3
Term: 2nd Term
Week: 14
Grade code: 3.3.3.LI.1
Strand code: 3
Sub-strand code: 3
Content standard code: 3.3.3.CS.2
Indicator code: 3.3.3.LI.1
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROMAGNETIC INDUCTION & APPLICATIONS
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This lesson explores Eddy currents, a fascinating and important consequence of Faraday's Law of electromagnetic induction. We will build upon our previous understanding of Lenz's law to see how changing magnetic fields can induce circulating currents within bulk conductors. While often seen as a source of energy loss in devices like the ECG transformers we see in our communities, Eddy currents are also harnessed for powerful applications, from modern cooking stoves to the brakes on high-speed trains. Understanding Eddy currents is crucial for designing efficient electrical machines and developing innovative technologies.
A. Recap: Faraday's and Lenz's Laws
Before we discuss Eddy currents, let's recall the two fundamental laws that govern them: Faraday's Law of Induction: States that a changing magnetic flux through a conducting loop induces an electromotive force (EMF) in the loop. The magnitude of the induced EMF is proportional to the rate of change of the magnetic flux. (ε ∝ -dΦ/dt). Lenz's Law: States that the direction of the induced EMF (and the resulting current) is always such that it creates a magnetic field that *opposes the change in magnetic flux that produced it*. This is the "law of electromagnetic inertia." B. What are Eddy Currents?
Definition: Eddy currents (also known as Foucault currents) are loops of electrical current induced within bulk conductors by a changing magnetic field in the conductor, according to Faraday's law of induction.
Explanation: Think about what happens when you stir a river. You see small, swirling whirlpools or "eddies." A similar thing happens with electrons in a solid piece of metal.