Unit 3: Magnetism Learning Targets for this Unit:  I can conduct an investigation to explain how magnetic fields are created  I can diagram (explain with words and pictures) how magnetism is a force of magnetic domains and magnetic fields.

Properties of Magnets zAll magnets have two areas of strongest force, called poles. zEach magnet has one north pole and one south pole. zLike poles repel, and opposite poles attract. zThe magnetic region where you can “feel the force” is called a magnetic field. Try out this interactive magnetic field link:

Magnetic Materials zWhat makes some things magnetic, while other things can’t be magnetized? zSpinning electrons cause small magnetic fields around each atom. zMagnetic materials have atoms whose magnetic fields can be lined up in the same direction. zAreas where atoms’ magnetic fields line up are called magnetic domains. ( magnetic domain ) z Randomly arranged domains = No magnet! z Magnetic domains lined up = Magnet!

Electricity & Magnetism zElectricity can cause magnetism! You can make a magnet by using electricity to magnetize the domains in iron. These are called electromagnets zElectromagnets are powerful magnets that can be turned on and off. You can make an electromagnet stronger by: (1) putting more turns of wire in the coil (2) making a larger soft iron core (3) increasing the current through the wire.

Let’s Try it!! zUsing an iron nail, wire, and a nine-volt battery, we will attempt to create an electromagnet that may be able to pick up some paper clips!

Uses for electromagnets zLET’S FIND OUT…. magnet.htm zRead the article and list at least three things that have electromagnets in them.

Let’s turn it around… Magnetism can create ELECTRICITY zMagnetism can produce electric current. This is called electromagnetic induction. zIf a magnet is moved back and forth through a coil of wire, current can be made to flow through the wire. This is the idea behind electric generators and transformers.

Uses for Electromagnetic Induction zDevices that use magnetism to induce currents include generators, pickup coils in electric guitars, transformers of every size, certain microphones, airport security gates, and damping mechanisms on sensitive chemical balances.

Using Electromagnets to Make Sound zHow does musical information stored on a CD become sound you can hear? zThe sound is produced by a loudspeaker that contains an electromagnet connected to a flexible speaker cone that is usually made from paper, plastic, or metal. zThe electromagnet changes electrical energy to mechanical energy that vibrates the speaker cone to produce sound

Earth’s Magnetosphere

Like many Planets in our Solar System the Earth has a Magnetic Field

The Earth behaves as if there was a magnet in its interior. The Earth’s magnetic field comes from the currents in the molten iron core. These currents create a complex magnetic field that ends up acting like a bar magnet S N

The North Pole of the Earth has a “south” polarity. As a result a compass will always point towards the North. A compass is a Magnetized piece of metal that can spin. S N

Try It zLook at a compass…can you find which way is north? zGo stand by the northern-most wall in the classroom zWhat happens when you get a magnet near a compass?

A Magnetic Field also protects us from the Solar Wind. The Sun produces a stream of charged particles that spread throughout the solar system. These particles are deflected by the Earth’s Magnetic Field

Read Article “Earth’s Magnetic Field Provides Vital Protection” Published March 8 th, 2012

The Earth’s Magnetic Field is created in the same way you make an electromagnet

4. The Inner Core: Solid Iron and Nickel 3. The Outer Core: Liquid Iron and Nickel 2. The Mantle: A Dense and Mostly Solid Rock Material 1. The Crust: A Thin Rock Material The Earth is made of four layers

The Iron Core of the Earth is an Electromagnet The core is surrounded by liquid Iron and Nickel As electrons flow around the core the magnetic field is produced The Earth’s rotation makes the electrons flow at very high speeds

Other Planets in our Solar System have Magnetic Fields PlanetMagnetic Field Mercury100 times weaker than Earth Venus25,000 times weaker than Earth Earth30,000 – 60,000 nT Mars5000 times weaker than Earth Jupiter20,000 times greater than Earth Saturn540 times greater than Earth Uranus40 times greater than Earth Neptune¼ that of Earth PlutoNone that we know of

Let’s see some visuals… Take a break to watch “Magnetic Storm: Earth's Invisible Shield “Magnetic Storm: Earth's Invisible Shield

Magnetism & the Sun: zAlmost everything in the universe is made up of atoms which are made of protons, electrons, and neutrons zHydrogen has one electron and one proton zThe Sun is made mostly of hydrogen zIn the right pressure environment, as solids are heated, they turn to liquids. Liquids, if heated enough, will turn to gas

Magnetism and the Sun zThe Sun is SO hot because gravity pulls its mass together so strongly that near the core of the sun atoms fuse together. This fusion converts Hydrogen to Helium and energy. This energy gets absorbed and turned into heat zThe Sun is SO hot that electrons cannot stay attached to the nucleus of the atoms. This means that the Sun is mostly a hot, electrically charged gas known as plasma zThe Sun’s magnetic field comes from currents in and around the Sun that are caused by the moving “plasma”

Read Article “The Sun” Published July 16, 2010

Planets and Magnetic Fields zHow do we measure the magnetic fields that exist between planets? zIf we wanted to learn more about the magnetic fields that are ejected by the Sun we could send a satellite into space with some way to measure the magnetic field…such as a compass or magnetometer zWe have to go into space to do this because the magnetic field of the Sun at Earth’s distance is 10,000 times less strong than the Earth’s own magnetic field so it interferes with true measurement of the Sun’s magnetic field

A planet’s magnetic field is measured using an instrument called a Magnetometer

Many spacecraft carry Magnetometers to measure the Magnetic Field. Advanced Composition Explorer Mars Global Surveyor Galileo Check out this clip about magnetometers

What is electromagnetic energy? Electromagnetic energy is a term used to describe all the different kinds of energies released into space by stars such as the Sun. These kinds of energies include: Radio WavesTV waves Radar wavesHeat (infrared radiation) Light X-rays Gamma Rays Ultraviolet Light (This is what causes Sunburns) Microwaves, like in a microwave oven

What is Electromagnetic Energy? (continued) All these waves do different things but they have some things in common. They all travel in a way that is like the waves at a beach They are made of tiny particles. We can measure the different kind by wavelength. That is one way we can tell the kinds of radiation apart from each other. Although all kinds of electromagnetic radiation are released from the Sun, our atmosphere stops some kinds from getting to us. For example, the ozone layer stops a lot of harmful ultraviolet radiation from getting to us, and that's why people are so concerned about the hole in it.