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: 12
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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Good morning, class. Today, we are going to study a device that is absolutely essential for our modern lives in Ghana: the transformer. Think about the electricity that powers our homes, schools, and businesses. It is generated far away at places like the Akosombo Dam or the Bui Dam. How does that power travel hundreds of kilometres to reach our light bulbs and phone chargers without losing most of its energy along the way? The answer lies in the transformer. Understanding how transformers work, why they are not perfectly efficient, and how we make them better is key to understanding our national power grid, managed by VRA, GRIDCo, and ECG.
2.1 What is a Transformer? A transformer is a static electrical device that transfers electrical energy from one alternating current (AC) circuit to another, either at a different voltage or current level.
Key Principle: It operates on the principle of mutual electromagnetic induction. An alternating current in the first coil (the primary coil) creates a continuously changing magnetic flux in the iron core. This changing magnetic flux links with the second coil (the secondary coil). According to Faraday's Law of Induction, this changing flux induces an alternating electromotive force (e.m.f.), and hence an alternating current, in the secondary coil.
Important Note: Transformers only work with AC. A DC current creates a constant magnetic field, not a changing one, so no induction occurs in the secondary coil.
Components: Primary Coil: The input coil connected to the AC source. Secondary Coil: The output coil connected to the load. Soft Iron Core: A core made of a ferromagnetic material that concentrates the magnetic flux, ensuring most of the flux from the primary coil links with the secondary coil.