Magnetism Notes – Know the * items * Magnetism is the force of attraction or repulsion. • A magnet is any object that exhibits the magnetic properties of attraction and repulsion. • Ferromagnetic metals , such as iron, are strongly attracted to magnets and can become magnets. You did this in the warm up activity.

Magnetism Notes You can make a magnet from something made of iron, cobalt or nickel if you can line up the domains, or clumps of atoms. • Every magnet has two poles—north and south— where the attraction is strongest. * Opposite poles attract; like poles repel.

Magnetism Notes Earth’s geographic north is its magnetic south pole; its geographic south is its magnetic north. (Also remember the idea from 6th grade about the magnetic poles flipping many times in history?) Every magnet has a magnetic field that runs in a loop from north to south poles, through the magnet, and around and around. When like poles are put together, they repel each other as they try to make their field lines line up in the same direction.

Magnetism Notes * Everything is made of atoms, which have a positively charged nucleus and negatively charged electrons orbiting the nucleus. So each atom is a mini-magnet. When electrons move, they create a magnetic field. • In the atoms of most materials, pairs of electrons spin in a way that cancels the magnetic field. • Electrons in magnets spin by themselves, with nothing to cancel the magnetic field.

Magnetism Notes * Magnets stick together because they align their fields to make bigger magnets. • Clumps of magnetic atoms are called domains. *So what makes a material magnetic is the fact that the domains in the object are aligned • Permanent magnets are always attracting and repulsing.

Magnetism Notes – 2 kinds 0f Magnets

Magnetism Notes – 2 kinds 0f Magnets * Electromagnetism is the interaction between electricity and magnetism. *An electromagnet is a temporary magnet that becomes a magnet when electricity is applied. • An electric motor uses electromagnets placed around permanent magnets.* The motor converts Electrical energy into mechanical Energy. An electromagnet can be made stronger by sending my electricity through it or adding more coils to the electromagnet

Magnetism Notes • Magnetism can be used to do things as varied as hold things together, propel vehicles down a track, and produce sounds through audio speakers

MAGNETS Enrichment Activities http://www.harcourtschool.com/activity/electromagnets/ http://www.harcourtschool.com/activity/science_up_close/504/deploy/int erface.html Exploratorium http://www.exploratorium.edu/snacks/iconmagnetism.html How Stuff Works: How Electromagnets Work http://www.howstuffworks.com/electromagnet.htm How Stuff Works: How Magnets Work http://science.howstuffworks.com/magnet.htm NOVA: Magnetic Storm http://www.pbs.org/wgbh/nova/magnetic/

TEST YOUR KNOWLEDGE OF MAGNETISM 1 A metal that is strongly attracted to a magnet is called ____. 2 Steel is an example of a ferromagnetic material. -------- 3 Every magnet has ___ where the attraction is strongest. 4 The rule for magnetic poles is : “ like poles ___; opposite poles ___.” 5 Earth has two magnetic poles. 6 Earth’s geographic north pole is _____. 7 Electrons are tiny _______. 8 In the atoms of most materials, pairs of electrons spin in a way that cancels the magnetic field. 9 A clump of magnetic atoms is called a _____. 10 If you cut a magnet into small pieces, the small pieces are no longer magnetic. 11 This type of magnet is always attracting and repulsing. 12 An electromagnet is a ____ magnet. 13 When electrons move, they create a _____. 14 You can make an electromagnet by coiling a wire around an iron rod. 15 An electromagnet becomes a magnet when electricity is turned on.

TEST YOUR KNOWLEDGE OF MAGNETISM ANSWER KEY 1 A metal that is strongly attracted to a magnet is called ____. Ferromagnetic 2 Steel is an example of a ferromagnetic material. true 3 Every magnet has ___ where the attraction is strongest. two poles 4 The rule for magnetic poles is : “like poles ___; opposite poles ___.” repel; attract 5 Earth has two magnetic poles. true 6 Earth’s geographic north pole is _____. it’s magnetic south pole 7 Electrons are tiny _____. magnets 8 In the atoms of most materials, pairs of electrons spin in a way that cancels the magnetic field. true 9 A clump of magnetic atoms is called a _____. domain 10 If you cut a magnet into small pieces, the small pieces are no longer magnetic. false 11 This type of magnet is always attracting and repulsing. permanent magnet 12 An electromagnet is a ____ magnet. temporary 13 When electrons move, they create a _____. magnetic field 14 You can make an electromagnet by coiling a wire around an iron rod. true 15 An electromagnet becomes a magnet when electricity is turned on. true