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Magnetism - Coggle Diagram

- - - - A steel bar is stroked in one direction along its length using 1 or 2 permanent magnets
      - The end of the steel bar where the stroke finishes acquires an opposite polarity to that of the end of the magnet
      - Magnetic domains
        
        They are microscopic clusters of atoms that have aligned magnetic fields.
        
        Within a material, there is more than 1 domain, which do not necessarily have aligned magnetic fields. When magnetic induction takes place, the magnetic fields within each domain will start to align, allowing the material to become a magnet
    - - A solenoid, which is a long coil of insulated copper wire is connected in series with a switch and a battery. The steel bar is inserted inside the solenoid and the switch is closed
      - A direct current passes through the solenoid, producing a strong magnetic field, which magnetises the steel bar into a magent
      - The poles of the magnetised steel bar can be determined using the right hand grip rule or by viewing the direction of current from each end (CW - South pole, ACW - North pole)
  - - - A low mains voltage, with an alternating current, is connected in series with a rheostat and a solenoid. The specimen to be demagnitised is then placed into the solenoid and the alternating current is turned on. After a while, the specimen is withdrawn from the solenoid to a long distance away and the specimen is demagnitised and becomes a magnetic material
- - - - They are drawn from the North to the South pole of a magnet
      - The closer the magnetic lines of force, the stronger the magnetic field of the magnet
      - They are unbroken lines that never cross each other
      - A uniform magnetic field is one where the strength and direction of the magnetic field is the same and it is represented by parallel lines of equal spacing
      - The lines for force tend to pass through magnetic materials as compared to non-magnetic material (application: magnetic shielding/screening)
      - The plotting compass can be used to indicate the direction of lines of forces as the North pole of the compass needle points in the same direction as magnetic field. This is because the compass needle itself is a tiny permanent magnet
- - - - It is the process whereby a material behaves like a magnet when it is placed in the external magnetic field of a magnet.
      - A magnetic material is always attracted to a magnet because magnetic induction takes place. This is because the end of the material closest to the pole of the magnet acquires an opposite polarity, thus induction precedes attraction