4.2 Magnetism

• Properties of a magnet (attractive, repulsive, poles, directional, magnetic strength)
• Basic law of magnetism
• Classification of materials as magnetic or non-magnetic
• Uses of magnets in day-to-day life

• demonstrate the properties of a magnet
• classify materials as magnetic or non-magnetic
• identify the uses of magnets in day-to-day life
• appreciate the applications of magnets in day-to-day life

“How are magnets used in day-to-day life?”

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1. What a magnet is
   40 min · 1 practice tasks · quiz
   A magnet attracts some metals and has two poles. Sixteen lessons run from properties to uses. Inquiry: how are magnets used in day-to-day life?
2. Attractive property
   40 min · 1 practice tasks · quiz
   A magnet pulls magnetic materials toward itself. Demonstrate with nails and pins. Paper and plastic stay put. Unity: share the magnet.
3. Repulsive property
   40 min · 1 practice tasks · quiz
   Two magnets can push apart. That push is repulsion. You need two magnets; a nail does not repel a magnet in this Grade 7 demo.
4. Poles of a magnet
   40 min · 1 practice tasks · quiz
   The poles are the two ends where magnetic behaviour is strongest, named North and South. Dip a magnet in pins: they crowd the ends.
5. Basic law of magnetism
   40 min · 1 practice tasks · quiz
   Like poles repel. Unlike poles attract. Investigate with two labelled magnets. Record four combinations if you have time.
6. Directional property
   40 min · 1 practice tasks · quiz
   A freely turning magnet lines up north-south. That is the directional property. A compass is the daily-life tool that uses it.
7. Magnetic strength
   40 min · 1 practice tasks · quiz
   Strength is greatest at the poles and differs between magnets. Compare by counting pins lifted. Do not hammer a magnet to strengthen it.
8. Magnetic and non-magnetic materials
   40 min · 1 practice tasks · quiz
   Magnetic materials are pulled by a magnet. Non-magnetic are not. Iron and steel versus paper, plastic, aluminium. Price is not the test.
9. Testing and classifying materials
   40 min · 1 practice tasks · quiz
   Use a permanent magnet to sort a junk tray into magnetic and non-magnetic. Record. Responsibility: return samples; do not magnet-sweep phones.
10. Magnets in fridge doors and compasses
    40 min · 1 practice tasks · quiz
    Daily uses start here: a fridge door seal or note magnet, and a magnetic compass. Feel a fridge gasket if the school has one; do not dismantle it.
11. Magnets in radios and speakers
    40 min · 1 practice tasks · quiz
    Radios and speakers use magnets as parts. Name the use. Do not open a live speaker or a plugged radio. Matatu sound still counts as daily life.
12. Magnets separate mixtures
    40 min · 1 practice tasks · quiz
    A magnet can pull iron from sand or scrap. Wrap it in polythene. This use also revisits mixture separation from 2.1.
13. Magnets in toys
    40 min · 1 practice tasks · quiz
    Toys use magnets for a magic effect: floating pieces, clicking trains, fishing games. Play is a use. Swallowing a magnet is not a use.
14. Searching magnet applications
    40 min · 1 practice tasks · quiz
    Search print or digital media for more uses beyond the design six. Share one real application. Do not copy a university motor page as if it were Grade 7.
15. Caring for magnets
    40 min · 1 practice tasks · quiz
    Keep keepers on bar magnets if you have them, store N against S of a pair, no heat, no hammer, no drop, no cards. Responsibility for the next class.
16. Appreciating magnets
    40 min · 1 practice tasks · quiz
    Close 4.2: properties demonstrated, materials classified, uses named, care practised. Answer the inquiry. Pre-Technical Studies continues magnet tools later.