Magnetism

20A Magnets and Magnetism

• Magnets

  • Magnet: any material or object that can produce a magnetic field

  • Magnetism: the properties of magnets and magnetic fields and phenomena that they produce

• Magnetic Properties

  • Magnetic Pole: one of the two regions of concentrated magnetic fields in a magnet; traditionally called the north and south poles

  • Magnetic Field: the region surrounding a magnet or current-containing wire that can apply a magnetic force on magnetic materials

• Earth’s Magnetic Field

  • Magnetic South Pole: the magnetic pole in the Southern Hemisphere. It is currently located beneath the Antarctic Ocean south of Australia. This pole is actually the north of Earth’s magnetic field

  • Magnetic North Pole: the magnetic pole in the Northern Hemisphere. It is currently located beneath the Arctic Ocean and is moving toward Siberia. This pole is actually the south pole of Earth’s magnetic field

  • Magnetic Declination: the angular difference between the directions to the geographic and magnetic North Poles

• Factors Affecting Magnetism

  • Magnetic Domain: a group of atoms whose individual magnetic fields are aligned

  • Ferromagnetism: the physical property in which a material’s magnetic domains spontaneously align to an external magnetic field

20B Electromagnetism

• Electric Current and Magnetism

  • Right-Hand Rule: a mnemonic device used to remember the direction of the magnetic field induced by an electric current moving through a wire

  • Solenoid: a coil of current-carrying wire used as a magnet

  • Electromagnet: the combination of a strong magnet and an electrified wire coil

  • Electromagnet Induction: the principle that voltage is produced in a conductor whenever the conductor whenever the conductor and a magnetic field are changed relative to each other

• Electromagnetism at Work

  • Heavy metal

  • People movers

  • Staying focused

  • Taking a peek inside

  • Music makers

  • Sorting it out

20C Generating and Using Electricity

• Generating Electricity

  • Generator: a device that converts mechanical energy into electrical energy by electromagnetic induction

  • Rotor: the rotating portion of a generator

  • Stator: the stationary portion of a generator

  • Prime Mover: the agent that provides the mechanical energy to turn the rotor of a generator

  • Commutator: a structure in DC motors and generators that converts currents between DC and AC

• Transmitting Electricity

  • Transformer: a device that uses electromagnetic induction to increase or decrease the voltage of an AC current

  • Step-Down Transformer: a transformer that is designed to decrease an output voltage

  • Step-Up Transformer: a transformer that is designed to increase an output voltage