Magnetic Forces | Prep.1 | Unit 2 - Lesson 2 | Science

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In This Part :
▌It is believed that the natural magnet rock (lodestone) was discovered in Magnesia (a regional unit) of Ancient Greece.
▌The natural magnet is characterized by its ability to attract certain metallic objects.
The shapes of artificial magnets vary, including:
Metallic materials are classified according to their attraction to magnets into :
Life Application :
Forensic and criminal investigation experts use magnetic brush and iron filings in criminal investigations to reveal the unclear fingerprints.
► The procedure:
1. The magnetic brush is brought close to the iron filings, which are attracted to it.
2. The brush is then passed over surfaces where the unclear fingerprints are
present.
3. Some iron filings stick to the traces left by the fingerprints, which making them visible.
Properties of Magnets
❶ The attraction force (magnetic forces) of a magnet is the strongest at its poles, and it decreases as it gets closer to the middle of the magnet.
❷ A magnet always takes a certain direction when it is suspended freely, influenced by the Earth.
When a magnet is suspended freely, it always takes a certain direction, where :
Life Application: The Compass
► It's structure:
A free-moving magnetic needle fixed at its pivot.
• Placed inside a copper or plastic box . . . G.R.?
To prevent the attraction between the needle and the box material, which can affect on its movement.
It's importance:
The compass is an old tool used to determine the Earth's four main geographical directions.
Law of Attraction and Repulsion
Law of Attraction and Repulsion
Like (similar) magnetic poles repel each other.
Unlike (different) magnetic poles attract each other.
Magnetic Field
The Magnetic Field
The region of space around a magnet where the effect of its magnetic force appears in it.
Magnetic Field Lines
They are imaginary lines that represent the force of the magnetic field.
Shapes of Magnetic Field Lines
From these shapes, the properties of the magnetic field lines can be concluded:
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