Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Describe Faraday's and Lenz's laws of electromagnetic induction.
• Demonstrate electromagnetic induction through an experiment.
• Identify historical contributions to this field.
• Apply these principles to real-world situations in Ghana.

Lesson summary

Welcome, future engineers and scientists! Today, we are exploring a magical idea that powers our modern world: Electromagnetic Induction. Have you ever wondered how the Volta River Authority (VRA) generates electricity at the Akosombo Dam, or how a simple generator lights up your house during a power outage ("dumsor")? The answer lies in the principles we will learn today. Electromagnetic induction is the process of generating an electric current using a changing magnetic field. It is the backbone of electricity generation, transformers on our ECG poles, and even the wireless chargers for our phones.

Lesson notes

2.1. Magnetic Flux (Φ)

Before we can understand induction, we must first understand magnetic flux. Definition: Magnetic flux is a measure of the total number of magnetic field lines passing through a given area. Think of it like the amount of rain falling through an open window. Formula: The magnetic flux (Φ) through an area (A) placed in a uniform magnetic field (B) is given by: `Φ = B * A * cos(θ)` B: Magnetic field strength (in Tesla, T) A: Area of the coil or loop (in square metres, m²) θ: The angle between the magnetic field lines and the *normal* (a line perpendicular) to the area A.

Key Idea: For induction to happen, this magnetic flux must *change*. You can change the flux by: Changing the magnetic field strength (B). Changing the area of the coil (A). Changing the orientation of the coil with respect to the field (changing the angle θ). 2.2. Faraday's Discovery and Law of Induction

Michael Faraday, a brilliant experimental physicist, discovered that magnetism could produce electricity. His experiments were simple but profound.

Evaluation guide

• Using experimentation, verify the laws of electromagnetic induction.
• Collaborative learning: In groups of mixed abilities, describe experiments to verify the laws
• of electromagnetic induction.
• Describe the observations of Faraday and the development of Faraday's law.