Basic Science and Technology - Junior Secondary 3 - Magnetism II

TERM: 2^ND TERM

WEEK: 8

CLASS: Junior Secondary School 3

AGE: 14 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Magnetism II

SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to

1. ) Discuss the care of magnets
2. ) In detail(step-by-step), explain how to make a magnet
3. ) State and explain the law of magnetism

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source

INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 3

INSTRUCTIONAL PROCEDURES: PERIOD 1-2:

NOTE

MAGNETISM

Care of Magnets:
Magnets, especially permanent ones, require careful handling to maintain their magnetic properties. Here are key guidelines for caring for magnets:

• Avoid Physical Damage: Dropping or hitting magnets can cause them to lose their magnetism or become demagnetized. Physical shock can disturb the alignment of the magnetic domains.
• Keep Magnets Away from High Temperatures: High heat can weaken or even destroy a magnet’s magnetic properties. Most permanent magnets lose their magnetism when heated above a certain temperature, known as the Curie point.
• Avoid Strong Magnetic Fields: Exposure to strong external magnetic fields can interfere with or even reverse a magnet’s polarity, demagnetizing it.
• Store Properly: Store magnets in a way that prevents them from coming into contact with materials that might demagnetize them. They should be kept in pairs, with opposite poles facing each other, to prevent loss of magnetism.
• Use Protective Coatings: Many magnets, especially those made from materials like iron, are prone to rusting. Using protective coatings (e.g., paint, plastic coverings) can help preserve their strength and prevent corrosion.

How to Make a Magnet (Step-by-Step):
To create a simple magnet, follow these steps:

• Step 1: Choose a Magnetic Material
  Select a ferromagnetic material like iron, nickel, or cobalt. A steel nail or iron rod works well for this purpose.
• Step 2: Align the Material with a Magnetic Field
  Take a strong magnet (either a permanent magnet or an electromagnet) and align the iron rod or nail with the magnetic field. Hold it firmly against the magnet or rub it along the length of the rod in one direction.
• Step 3: Stroke in One Direction
  Stroke the magnet along the rod or nail in a single direction, applying pressure. Repeat this process about 30-50 times. Each stroke should be in the same direction to align the magnetic domains in the material.
• Step 4: Test the Magnet
  After stroking the iron rod or nail, test it by bringing it close to small metallic objects like paper clips or pins. If the object sticks, the rod has been successfully magnetized.
• Step 5: Store the Magnet Properly
  Store the newly magnetized material in a safe place, keeping it away from heat and strong magnetic fields to prevent it from losing its magnetism.

Law of Magnetism:
The Law of Magnetism describes how magnetic forces interact between objects. It can be summarized as follows:

• Like Poles Repel: Two magnets with the same poles (e.g., north-north or south-south) will repel each other. This happens because the magnetic field lines are oriented in such a way that they push away from each other.
• Opposite Poles Attract: Two magnets with opposite poles (e.g., north-south) will attract each other. The opposite poles are drawn together because their magnetic field lines combine and move in the same direction, pulling the objects toward each other.
• Magnetic Force Decreases with Distance: The force of attraction or repulsion between two magnets decreases as the distance between them increases. The closer the magnets are, the stronger the force of attraction or repulsion

EVALUATION:

1. Why is it important to store magnets properly, and how does improper storage affect their magnetic properties?
2. Describe the step-by-step process of making a magnet and explain why it's necessary to stroke the material in one direction.
3. How do high temperatures and strong external magnetic fields impact the strength of a magnet?
4. Explain the Law of Magnetism: What happens when two magnets with like poles are brought close to each other?
5. What is the relationship between the distance between two magnets and the magnetic force between them, according to the Law of Magnetism?

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively