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