Physics (2)

Nota:

• Magnetism

1. All magnets have a north and south pole
2. Domains

   Nota:

   • A magnetic domain is region in which the magnetic fields of atoms are grouped together and aligned. In a non-magnetic materials, the domains are randomly orientated. In magnetic materials, the domains are regularly aligned
3. Field lines

   Nota:

   • Flow from the North to South poles of the bar magnet.
4. Magnetic substances

   Nota:

   • Magnets have "power" to attract and repel. Magnetic Materials only can be attracted to magnets.
   1. Iron
   2. Nickel
   3. Cobalt
   4. Hard & Soft magnetic materials

      Nota:

      • Materials which retain their magnetism and are difficult to demagnetize are called hard magnetic materials. Soft magnetic materials are easy to magnetize and demagnetize.
5. Opposite poles attract, like poles repel
6. Making magnets

   Nota:

   • Magnets are made by exposing magnetic materials like iron and nickel to magnetic fields. 
7. Electromagnet

   Nota:

   • A soft metal core made into a magnet by the passage of electric current through a coil surrounding it.
   1. Make stronger

      Nota:

      • Connect your batteries in series so you have more voltage, and thus more current through your electromagnet More coils of wire 
   2. Uses

      Nota:

      • Televisions Traditional television sets use an electromagnet to power the cathode ray tube. The electromagnet directs the beaming of electrons, which in essence illuminates the television. Computer Screens Before the advent of LCD and plasma, the electromagnet was an essential part of computer monitors. The electromagnet bends the electrons when they pass through the screen, which is how the image on the screen is prepared. Automobiles Electromagnets are used in automobiles. The electromagnet is essential to the starter motor. Also, the ignition coil is an enhanced electromagnet. Electromagnets are used in the self-closing mechanism found in some automobile doors. MotorsElectromagnets are used in many motors. Electric motors have an electromagnet as an integral part of their circuitry. Electromagnets are used in ceiling fans, in the fans installed inside computers and in generators.SoundIf you have ever used a loudspeaker, you have heard an electromagnet in use. If you have an MP3 player or another portable audio device and use earphones to listen to music, you have used an electromagnet. An electromagnet draws the speaker diaphragm, allowing the music to be played.ScrapyardsIn scrapyards, electromagnets lift cars and other magnetic objects.Fire Doors and Automatic DoorsFire doors and doors that closes automatically both use electromagnets.RelaysElectromagnets are used in relays, as switches that control the relay. Electromagnetic relays were used in traditional telephones as well as the first computers.Sorting MetalsElectromagnets are used to sort metals.TransportElectromagnets are used to power some trains.
   3. How it works ?

      Nota:

      • Bell 1. Complete circuit 2. Current flows 3. Electromagnet turns on 4. Soft iron arm attracted 5. Breaks the circuit at contacts 6. Current stops flowing 7. Electromagnet off 8. Springs arm back. 9. ↨