What is a Magnet What Materials are Magnetic

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What is a Magnet? What Materials are Magnetic?

What is a Magnet? What Materials are Magnetic?

What Materials are Magnetic?

What Materials are Magnetic?

What Do Magnets Do? üAttract or repel other magnets (exert a force) üAttract other

What Do Magnets Do? üAttract or repel other magnets (exert a force) üAttract other magnetic metals üHave at least 2 distinct ends (poles) each Like poles repel, opposite poles attract Notes: §Do not need to touch to exert force (can exert force through empty space) §Can turn other magnetic metal objects into temporary magnets

Magnets have been known for centuries. The Chinese and Greeks knew about the “magical”

Magnets have been known for centuries. The Chinese and Greeks knew about the “magical” properties of magnets. The ancient Greeks used a stone substance called “magnetite. ” They discovered that the stone always pointed in the same direction. Later, stones of magnetite called “lodestones” were used in navigation.

William Gilbert, an English physician, first proposed in 1600 that the earth itself is

William Gilbert, an English physician, first proposed in 1600 that the earth itself is a magnet, and he predicted that the Earth would be found to have magnetic poles.

What is Magnetism? Magnetism is the force of attraction or repulsion of a magnetic

What is Magnetism? Magnetism is the force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons.

What is a Force? Force is a push or pull that causes a change

What is a Force? Force is a push or pull that causes a change in motion. Electric field of 2 like charges A Force Field is the pattern in space of how that force is felt by other objects. Fundamental Forces arise from fundamental properties of matter: Gravity arise from Mass: mass attracts mass Electric force arises from Gravitational field of a point of mass Charge: two kinds of charge (positive and negative), like charges repel and opposite charges attract Electric field of 2 opposite charges

The ends of a magnet are where the magnetic effect is the strongest. These

The ends of a magnet are where the magnetic effect is the strongest. These are called “poles. ” Each magnet has 2 poles – 1 north, 1 south.

Like repels like… Opposites attract!

Like repels like… Opposites attract!

Poles of a magnet always Come in pairs!

Poles of a magnet always Come in pairs!

If you cut a magnet in half, you get 2 magnets!

If you cut a magnet in half, you get 2 magnets!

Magnetic Fields The region where the magnetic forces act is called the “magnetic field”

Magnetic Fields The region where the magnetic forces act is called the “magnetic field”

¶Atoms themselves have magnetic properties due to the spin of the atom’s electrons. ¶Groups

¶Atoms themselves have magnetic properties due to the spin of the atom’s electrons. ¶Groups of atoms join so that their magnetic fields are all going in the same direction ¶These areas of atoms are called “domains”

When an unmagnetized substance is placed in a magnetic field, the substance can become

When an unmagnetized substance is placed in a magnetic field, the substance can become magnetized. This happens when the spinning electrons line up in the same direction.

An unmagnetized substance looks like this…

An unmagnetized substance looks like this…

While a magnetized substance looks like this…

While a magnetized substance looks like this…

Magnetic Field Magnetic field of a Bar Magnet: 2 poles, called North and South

Magnetic Field Magnetic field of a Bar Magnet: 2 poles, called North and South Dipole field Field has direction: lines point away from N and toward S Definition of a Pole: Where lines meet (converge) e. g. : lines of longitude on a globe meet at poles

Earth: A Huge Bar Magnet Moving molten iron in Earth’s outer core causes most

Earth: A Huge Bar Magnet Moving molten iron in Earth’s outer core causes most of Earth’s magnetic field. Magnetic field poles are NOT aligned with geographic poles. They also wander and flip (500, 000 yrs between flips, 10, 000 yrs to complete flip).

The Earth is a magnet: It exerts magnetic forces and is surrounded by a

The Earth is a magnet: It exerts magnetic forces and is surrounded by a magnetic field that is strongest near the North and South magnetic poles Magnetic South Pole Geographic North Pole Magnetic North Pole

Sometimes, the Earth’s magnetic poles flip. This happens every halfmillion years or so. Magnetic

Sometimes, the Earth’s magnetic poles flip. This happens every halfmillion years or so. Magnetic North Pole Magnetic South Pole

We use the Earth’s magnetic field to find direction. The needle of a compass

We use the Earth’s magnetic field to find direction. The needle of a compass always points toward the magnetic south pole. We call this direction “North” (remember, opposites attract)

The sun has a magnetic field, too. It extends far above the sun’s surface.

The sun has a magnetic field, too. It extends far above the sun’s surface. Other planets in the solar system also have these magnetic fields

When a charged particle enters a magnetic field, an electric force is exerted on

When a charged particle enters a magnetic field, an electric force is exerted on it. If a charged particle moves at an angle to a magnetic field, the magnetic force acting on it will cause it to move in a spiral around the magnetic field lines.

The solar wind is constantly bombarding the Earth’s magnetic field. Sometimes these charged particles

The solar wind is constantly bombarding the Earth’s magnetic field. Sometimes these charged particles penetrate that field. These particles are found in two large regions known as the Van Allen Belts.

The Earth’s magnetic field extends far into space. It is called the “magnetosphere. ”

The Earth’s magnetic field extends far into space. It is called the “magnetosphere. ” When the magnetic particles from the sun, called “solar wind”, strike this magnetosphere, we see a phenomenon called…

The Aurora Borealis in the Northern Hemisphere And the Aurora Australis in the Southern

The Aurora Borealis in the Northern Hemisphere And the Aurora Australis in the Southern Hemisphere