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Magnetism & Electromagnetism
Magnet Earth
Chapter 1
Section 2
Earth’s Magnetic Field
• Just like a magnet • Due to molten metal circulating in the core of the earth– Iron– Nickel
Compass
• A devise with a magnetized needle that can spin freely
• Needle aligns with Earth’s magnetic field
Two Types of Poles
• Geographic “True” Poles– Perpendicular to
equator– Rotation of earth
• Magnetic Poles– Magnetic field
Magnetic Declination
• The difference in angle between the direction towards the Geographic & Magnetic poles.
Changing Magnetic Pole
• From 1580 to 1820 the Magnetic Declination for a sailor in London changed 35 degrees
Magnetosphere
• Protects the earth from solar winds– Electrically charge
particles in space
Aurora
• Borealis– Northern Lights
• Australis– Southern Lights
• Solar winds interact with atoms in earth’s atmosphere– Atoms release light
Earth Creates Magnets
• Because Earth is a magnet, it can create magnets
• Over many years, large metal objects can become magnetized by the earth if they are left undisturbed– E.g. file cabinets
Mid-Atlantic RidgeEarth’s Magnetic Reversals
• Roughly every 200,000 years– Not yet understood