Lesson Notes By Weeks and Term v4 - SHS 1
MAGNETOSTATICS
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MAGNETOSTATICS
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Subject: Physics
Class: SHS 1
Term: 2nd Term
Week: 12
Grade code: 1.3.2.LI.1
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.2.CS.2
Indicator code: 1.3.2.LI.1
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: MAGNETOSTATICS
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Magnets are more than just toys we stick on the fridge. They are essential to our modern lives here in Ghana. From the motors in the fan that cools us down and the blender that prepares our food, to the powerful cranes at Tema Harbour that lift heavy containers, magnetism is at work all around us. In this lesson, we will explore the fundamental question: "How do things become magnetic, and how can they lose that magnetism?" Understanding this is the first step to understanding how countless devices, from simple electric bells to complex medical equipment, function.
A. What Makes a Material Magnetic? The Domain Theory
Not all materials can be turned into strong magnets. Those that can are called ferromagnetic materials. The most common ones are Iron (Fe), Nickel (Ni), Cobalt (Co), and their alloys like Steel.
To understand how these materials become magnets, we use the Domain Theory. Definition: A magnetic domain is a microscopic region within a magnetic material where the magnetic fields of individual atoms are aligned in the same direction, acting like a tiny magnet. In an Unmagnetized Material: Imagine a busy marketplace like Makola or Kejetia. People are moving in all directions. There is a lot of activity, but no overall direction of movement. Similarly, in an unmagnetized piece of iron, there are millions of tiny magnetic domains. However, these domains are all pointing in random directions. Because they are randomly oriented, their magnetic effects cancel each other out. The overall material shows no magnetism.
Diagram: Unmagnetized Material ``` [ → ↓ ← ↑ ↘ ↖ ↙ → ] [ ↙ ↑ → ↓ ↖ ← ↗ ↘ ] [ ↑ ← ↘ ↗ ↓ → ↙ ← ] ``` *(Domains are pointing in random directions, cancelling each other out.)* In a Magnetized Material: Now, imagine a national parade at the Black Star Square. All the soldiers are marching in perfect formation, in the same direction. Their individual movements combine to create one large, powerful, organised movement. When a ferromagnetic material is magnetized, an external magnetic field causes the domains to align and point in the same direction. Their individual magnetic effects now add up, creating a strong overall magnetic field. The material is now a magnet with a clear North and South pole.