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: 10
Grade code: 1.3.1.LI.1
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.1.CS.1
Indicator code: 1.3.1.LI.1
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: MAGNETOSTATICS
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Magnets are not just toys; they are all around us and are fundamental to how our modern world works. From the speakers in the tro-tro that play our favourite music to the powerful motors in a blender used to prepare fresh juice or a fufu pounding machine, magnets are working silently. Even in our pockets, our smartphones use tiny magnets to function. In this lesson, we will begin our journey into Magnetostatics, the study of stationary (non-moving) magnets and their effects. By understanding the basic rules of how magnets behave, we can understand the technology that powers our communities.
(30 minutes)
This is the main content delivery part of the lesson. The teacher should use the TLRs to demonstrate these concepts. A. What is Magnetostatics? Magnetostatics is the branch of physics that studies magnetic fields created by stationary (non-moving) magnets or steady electric currents. The word 'statics' means 'not moving'. So, we are looking at the properties of magnets that are at rest. This is similar to *electrostatics*, where you studied stationary electric charges. B. Magnetic Poles: The Two "Personalities" of a Magnet Every magnet has two ends where its magnetic strength is concentrated. These ends are called magnetic poles. North Pole (or North-seeking pole): If you hang a magnet from a string so it can swing freely, one end will always point towards the Earth's geographic North. This end is called the North pole. South Pole (or South-seeking pole): The other end, which points towards the Earth's geographic South, is called the South pole.
Key Difference from Electric Charges: While you can have an isolated positive (+) or negative (-) charge, you can never have an isolated magnetic pole. If you cut a bar magnet in half, you do not get a separate North pole and a separate South pole. Instead, you get two smaller magnets, each with its own North and South pole. C. The Fundamental Law of Magnetism This is the most important rule governing how magnets interact. It is very similar to the law of charges. > Law: *Like poles repel each other, while unlike poles attract each other.* North repels North (N ↔ N) South repels South (S ↔ S) North attracts South (N → ← S)
*(Teacher Demonstration: Use two bar magnets to show attraction and repulsion clearly. Let students feel the force.)* D. Properties of Magnets Attractive Property: Magnets attract certain materials, known as ferromagnetic materials. The most common ones are Iron (Fe), Nickel (Ni), and Cobalt (Co). A magnet will not attract wood, plastic, rubber, or copper. *Ghanaian Context:* A small magnet can be used to separate iron filings that may have accidentally mixed with gari or sugar. Directive Property: As mentioned earlier, a freely suspended magnet will always align itself in a North-South direction. This is because the Earth itself acts like a giant bar magnet. *Application:* This is the principle behind the magnetic compass, which has been used for centuries for navigation by sailors, explorers, and even today in our smartphones. Inductive Property (Magnetic Induction): A magnet can make a ferromagnetic material (like an iron nail) behave like a magnet temporarily, without even touching it. When you bring a strong magnet near an iron nail, the nail becomes a magnet itself and can pick up other small items like paper clips. When the strong magnet is removed, the nail loses most of its magnetism. E. Magnetic Field and Magnetic Field Lines Magnetic Field: This is the region of space around a magnet where its magnetic influence can be felt. You can't see it, but you can detect it with another magnet or a compass. *Analogy:* Think of the area around a hot coal pot. You can feel the heat even without touching the pot. The magnetic field is like that "field of influence" for a magnet. Magnetic Field Lines (or Lines of Force): We use imaginary lines to visualise the magnetic field. These lines show the direction and strength of the field. *(Teacher Demonstration: Place a bar magnet under a sheet of cardboard. Sprinkle iron filings on top. Tap the cardboard gently. The filings will align themselves along the magnetic field lines, revealing the pattern.)*