Mada za sehemu hiiDemonstrate a basic understanding of types of energy and their usesMada 1
- Explain the concept of magnetism (meaning, properties and applications)
Concept of Magnetism
Magnetism is the ability of a magnet to attract or pull objects made of iron-related materials towards it. This pull is called magnetic force.
A magnet is a device that has the ability to attract objects made of iron-related materials such as iron, nickel, and cobalt. Every magnet has two special ends called poles — the North pole (N) and the South pole (S). The area around a magnet where magnetic force can be felt is called the magnetic field.
Worked Example: Identifying Magnetic Attraction
Imagine you have a bar magnet and you bring it near the following objects: a plastic ruler, iron paper clips, a piece of wood, a chalk piece, and a steel nail.
- The magnet will attract the iron paper clips and the steel nail (they are iron-related materials).
- The magnet will not attract the plastic ruler, wood, or chalk (they are not iron-related).
This shows that magnets only attract materials containing iron, nickel, or cobalt.
Magnets have important properties:
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Attraction: Magnets attract objects made of iron-related materials like iron, nickel, and cobalt.
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Poles: Each magnet has two poles — North (N) and South (S). The magnetic force is strongest at the poles.
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Like poles repel, unlike poles attract:
- North pole and North pole → repel (push away)
- South pole and South pole → repel
- North pole and South pole → attract (pull together)
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Magnetic field: Magnets are surrounded by an invisible force field. This field can be seen when iron filings are sprinkled around a magnet — the filings arrange themselves in curved lines.
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Penetration: Magnetic force can pass through different materials like paper, water, glass, and plastic.
Magnets come in different shapes depending on their use:
- Bar magnet — rectangular shape
- Horseshoe (U-shaped) magnet — curved like a horseshoe
- Ring magnet — circular with a hole in the middle
- Cylindrical magnet — shaped like a tube
Magnets are used in many everyday devices and activities:
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Lifting heavy objects: At ports and factories, large magnets lift iron and steel objects.
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Electronic devices: Radios, phones, computers, and refrigerators use magnets.
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Electric bells: Magnets help produce sound when the bell rings.
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Compass: A compass has a magnet that always points north, helping people find direction.
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Bicycle dynamo: A magnet rotates inside to generate electricity for the bicycle light.
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Separating materials: Magnets separate iron particles from other materials (like flour or soil) in food industries.
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Magnetic screwdrivers: Technicians use magnetic screwdrivers to hold small screws.
To keep magnets strong, follow these rules:
- Keep magnets away from iron objects
- Do not store like poles facing each other
- Do not burn or hammer magnets
- Keep magnets away from strong electricity
- Store magnets properly when not in use
In Tanzania, magnets are used in many ways. For example, at Mikoko Market in Dar es Salaam, sellers use small magnets to check if metal containers are made of iron. Also, many households have refrigerators with magnets on the door edges to keep the door closed tightly. If a student's bicycle has a dynamo light, they are using a magnet to generate electricity for the lamp when cycling.
Swali
What is magnetism?
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