Magnetism

What is magnetism? Magnetism-a force between magnetic objects Magnetism depends on the arrangement of atoms in an object Think back to atomic structure...

Atoms Nucleus Middle of the atom Protons have positive charge Neutrons have no charge Electrons Move around the nucleus Have a negative charge

Importance of Electrons When electrons move, they create a magnetic field Electrons constantly move around the nucleus Each atom becomes a tiny magnet Magnetic fields surround every magnet

Magnetic Fields All magnets have 2 poles, North and South The magnetic force is strongest at the poles The force also extends from the poles around the magnet

Pole Interactions Magnetic poles interact in predictable ways Poles that are different will attract (move together) Poles that are alike will repel (move away)

Atoms as Magnets Every object is made of billions of atoms Each atom has its own magnetic field In most objects (unmagnetized), these fields point in different directions When these fields line up in the same direction they make magnetic domains and the object becomes magnetized

Magnetic Materials The larger the magnetic domains an object forms, the stronger the magnet Certain materials do this naturally We call these Ferromagnetic Materials Iron, Nickel and Cobalt are the most common ferromagnetic materials

Types of Magnets Magnets can be either Permanent or Temporary Permanent magnets are objects whose magnetic domains are stable and keep their magnetism over time Temporary magnets are objects whose magnetic domains are unstable and lose their magnetism over time

Permanent Magnets What would happen if you broke a permanent magnet in half? You end up with 2 new magnets each with a new N and S pole Can magnets lose their magnetism? If they are dropped, struck or heated These cause the atoms to move which changes the magnetic domain’s position

Temporary Magnets When a strong magnet is placed close to a magnetic object... The magnetic domains will align and the object will be attracted to the magnet (paper clips) When removed from the magnet, the domains go back to normal These objects are temporary magnets

Uses of Magnets We use magnets in many every day objects Telephones, computers, lights Mag-Lev trains Roller coasters-Volcano, Flight of Fear, Intimidator 305 etc

Electromagnets When electricity is run through a wire, it creates a magnetic field When the electricity is turned off, the magnetic field goes away