Lesson Notes By Weeks and Term v4 - SHS 2
ELECTROMAGNETISM
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ELECTROMAGNETISM
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Subject: Physics
Class: SHS 2
Term: 2nd Term
Week: 7
Grade code: 2.3.2.LI.2
Strand code: 3
Sub-strand code: 2
Content standard code: 2.3.2.CS.1
Indicator code: 2.3.2.LI.2
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROMAGNETISM
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Welcome, students. Today, we are exploring a fascinating and powerful principle called electromagnetism. This isn't just an abstract topic in a textbook; it is the force that powers much of our modern world. Have you ever used a blender to make a smoothie, felt the breeze from a standing fan on a hot afternoon, or heard the sound from a loudspeaker at church or in a taxi? All of these devices work because of the force we will study today: the force on a wire carrying electricity when it is placed in a magnetic field. This is often called the motor effect.
Concept 1: The Motor Effect When an electric current flows through a conductor (like a copper wire), it creates its own magnetic field around the wire. If you place this wire into an external magnetic field (e.g., between the North and South poles of a magnet), the two magnetic fields interact. This interaction produces a force that pushes the wire.
In simple terms: The Motor Effect is the force experienced by a current-carrying conductor when placed in an external magnetic field.
This force is what makes electric motors spin. Concept 2: Direction of the Force - Fleming's Left-Hand Rule The force produced is a vector, meaning it has both magnitude and direction. To easily find the direction, we use Fleming's Left-Hand Rule.
Hold your left hand so that your thumb, forefinger (index finger), and centre finger are all at right angles (90°) to each other. Your Thumb points in the direction of the Thrust or Force (F) on the wire. Your Forefinger points in the direction of the magnetic Field (B), from North to South. Your Centre finger points in the direction of the conventional Current (I), from positive to negative.