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: 9
Grade code: 3.3.3.LI.3
Strand code: 3
Sub-strand code: 3
Content standard code: 3.3.3.CS.1
Indicator code: 3.3.3.LI.3
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROMAGNETIC INDUCTION & APPLICATIONS
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This lesson explores the fascinating principle of Electromagnetic Induction, which is the foundation of how we generate most of the electricity we use in Ghana. From the massive turbines at the Akosombo and Bui Dams to the small backup generator used during a power outage ('dumsor'), the ability to create electricity from magnetism is one of the most important discoveries in physics. We will learn how moving a wire in a magnetic field can produce a current, what factors make this current stronger or weaker, and how to predict its direction. Understanding this is key to understanding our modern, electrified world.
2.1 What is Electromagnetic Induction?
In our previous lessons, we learned that an electric current can produce a magnetic field (electromagnetism). The English scientist Michael Faraday wondered if the reverse was true: Can a magnetic field produce an electric current? The answer is yes, but with a crucial condition: the magnetic field must be *changing*.
Definition: Electromagnetic Induction is the process of producing an electromotive force (e.m.f.) and hence a current in a conductor, by changing the magnetic field around it. Induced e.m.f. (ε): The potential difference or voltage created across the ends of the conductor due to electromagnetic induction. It is measured in Volts (V). Induced Current (I): The flow of charge that results from the induced e.m.f. when the conductor is part of a closed circuit. It is measured in Amperes (A).
Key Idea: To induce an e.m.f., there must be relative motion between a conductor and a magnetic field. It doesn't matter if the magnet moves and the wire is still, or if the wire moves and the magnet is still. What matters is that the conductor is "cutting" through the magnetic field lines. 2.2 Faraday's Laws of Electromagnetic Induction