1. Ch. 8 - Magnetism I. Characteristics of Magnets  Magnetism  Magnetic poles  Magnetic field  Magnetic domain

2. A. Magnetism  Magnetism  force of attraction or repulsion between unlike or like poles  due to the arrangement of electrons  closely related to electricity

3. B. Magnetic Poles  Magnetic Poles  like poles repel  unlike poles attract  a broken magnet creates new poles

4. C. Magnetic Field  Magnetic Field  area around a magnet where magnetic forces act  field lines show direction of field (N  S)

6. D. Magnetic Domain  Magnetic Domain  groups of atoms with aligned magnetic poles  in a magnetized object, domains are all aligned domain

7. Strength of magnets and magnetic fields  Attraction and repulsion of magnets increases as they get closer to one another  …and decreases as they get farther apart.  Magnetic fields are strongest at the poles.

8. Permanent magnets  Not all metals can become magnetic. Aluminum foil – for instance, does not.  Iron, cobalt and nickel are the only metals that can become magnets.  Permanent magnets are created when these metals are placed within a strong magnetic field.

9. Loss of magnetism  Permanent magnets can lose their magnetism when heated  …or when they suffer a large impact.

10. Ch. 8 - Magnetism II. Uses of Magnetic Fields  Electromagnet  Speaker  Motor

11. A. Electromagnet  Electromagnet  strong, temporary magnet formed when current is passed through a coil of wire surrounding an iron core  acts like a bar magnet when current is on

12. B. Speaker  Speaker  electrical energy  mechanical energy  wire coil moves back & forth as its magnetic field interacts with a fixed magnet  forced vibration causes the cone to move  sound

13. C. Motor  Motor  electrical energy  mechanical energy  electromagnet rotates between the poles of a fixed magnet  commutator reverses the poles of the e’magnet

14. C. Motor brushes & wires to battery field magnet armature & commutator assembled motor

15. D. Galvanometers  Devices that use electromagnets to measure electric current (ex. sensors or gauges in your car.

16. Ch. 8 - Magnetism III. Producing Electric Current Electromagnetic Induction  Electric Generator  DC & AC  Transformer

17. A. Electromagnetic Induction  Electromagnetic Induction  producing a current by moving a wire through a magnetic field  some microphones work just like mini- speakers in reverse  sound waves cause coil to move  current Dynamic Microphone Coil

18. B. Electric Generator  Electric Generator  mechanical energy  electrical energy  armature is rotated between magnet poles  magnetic field induces a current in the wire coil MOTOR GENERATOR

19. B. Electric Generator  Hydroelectric Dam  PE of lake water is converted to KE  mechanical KE turns the generator shaft which creates electrical energy

20. C. DC & AC  Direct Current (DC)  current flows in one direction  dry cells  Alternating Current (AC)  current reverses its direction at regular intervals  electrical outlets

21. D. Transformer  Transformer  increases or decreases AC voltage  primary coil AC produces a magnetic field that induces AC in the secondary coil  voltage ratio = ratio of turns in each coil

22. D. Transformer  Step-up Transformer  increases the voltage  more turns  power plants  Step-down Transformer  decreases the voltage  fewer turns  household appliances (hairdryers, etc.)