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.2
Strand code: 3
Sub-strand code: 3
Content standard code: 3.3.3.CS.1
Indicator code: 3.3.3.LI.2
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROMAGNETIC INDUCTION & APPLICATIONS
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Welcome, future scientists and engineers! Almost every day, we use electricity provided by the Electricity Company of Ghana (ECG). We power our phones, lights, TVs, and businesses. But have you ever stopped to ask the fundamental question: where does this electricity come from? How is it generated at the Akosombo Dam or the Bui Dam, or even from the small generator ('gen-set') used during a power outage ('dumsor')? The answer lies in a fascinating principle called Electromagnetic Induction. This is the process of generating electricity using magnetism. It is one of the most important discoveries in physics, forming the basis of our modern electrical world.
A. What is Magnetic Flux (Φ)?
Before we can understand induction, we need to understand magnetic flux.
Imagine you are holding a bucket out in the rain. The amount of rain entering the bucket depends on three things: How hard it is raining (the strength of the rain). The size of the bucket's opening (the area). The angle at which you hold the bucket (if you tilt it, less rain gets in).
Magnetic flux is similar. It is a measure of the total number of magnetic field lines passing through a given area. Definition: Magnetic flux (Φ) is the product of the component of the magnetic field strength (B) perpendicular to a surface and the area (A) of that surface. Formula: ``` Φ = B * A * cos(θ) ``` Where: Φ (phi) is the magnetic flux, measured in Webers (Wb). B is the magnetic field strength (or magnetic flux density), measured in Tesla (T). A is the area of the surface (e.g., the area of a coil of wire), measured in square metres (m²). θ (theta) is the angle between the magnetic field lines and the normal (a line perpendicular) to the surface area. Important Note: When the magnetic field is perpendicular to the surface, the angle with the normal is 0°, and cos(0°) = 1. This gives the maximum flux: Φ = BA. When the field is parallel to the surface, the angle with the normal is 90°, and cos(90°) = 0. The flux is zero. B. The Discovery: Electromagnetic Induction