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.3
Strand code: 3
Sub-strand code: 2
Content standard code: 2.3.2.CS.1
Indicator code: 2.3.2.LI.3
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROMAGNETISM
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This lesson explores the fascinating interaction between electricity and magnetism, a principle that powers much of our modern world. We will learn about the "motor effect," which is the force experienced by a wire carrying an electric current when it is placed in a magnetic field. Understanding this principle is crucial because it is the foundation for electric motors found in everyday appliances in our homes and communities, from the fan that cools us down to the blender in the kitchen and the speakers that play our favourite music. By mastering this concept, you will gain a deeper understanding of how many essential technologies work.
Part A: The Motor Effect and Fleming's Left-Hand Rule The Fundamental Principle (The Motor Effect) When a wire carrying an electric current is placed within a magnetic field, it experiences a force. This is because the current in the wire generates its own magnetic field, which then interacts with the external magnetic field. This interaction results in a push or pull on the wire. This phenomenon is called the motor effect.
The direction of this force depends on two things: The direction of the electric current. The direction of the magnetic field.
To easily determine the direction of the force, we use a rule called Fleming's Left-Hand Rule. Fleming's Left-Hand Rule This rule is a mnemonic—a memory aid—that helps us remember the relationship between the directions of Force, Magnetic Field, and Current.
How to Use the Rule: Hold your left hand and point your thumb, forefinger (index finger), and centre finger so they are all at right angles (90°) to each other, like this: