Magnetism

• Name three magnetic materials

  iron, nickel, cobalt
• What happens when unlike poles are brought together?

  They attract
• What happens when like poles are bought back together?

  They repel
• What is a magnetic field?


  The area of magnetic force around a magnet in which a magnetic material would experience a force
• Where is the magnetic field the strongest?

  At the poles
• Where is the magnetic field the weakest?

  middle
• What happens to the strength of the magnetic field as you get further away from the magnet?

  It gets weaker (It gets stronger the closer you are to it)
• What does the distance between magnetic field lines tell us?

  The strength of the magnetic field; closer the lines, the stronger the field
• In which direction do magnetic field lines always point?

  From north to south
• What is a permanent magnet?


  A material that always has its own magnetic field
• What is an induced magnet?

  A material that becomes magnetic when it is placed in a magnetic field
• What does a compass contain?

  A bar magnet
• How can a compass be used to show a magnetic field?

  Compass needle aligns with magnetic field (north needle points toward south pole
• What causes Earth's magnetic field?

  Outer core
• What is produced around a wire when a current flows through it?

  Magnetic field
• How can you work out the direction of the magnetic field around a wire?

  Right hand rule
• There are three ways to increase the strength of the magnetic field around the wire. What are they?

  1.Coil wire into solenoid (more coils, stronger field)

  2.Add iron core (now called electromagnet)

  3.Increase current
• Name two advantages of using electromagnets over permanent magnets

  1.Can be turned on and off

  2.Strength of magnet can be increased/decreased
• What is the motor effect?(HT)

  When a wire carrying a current is placed in a magnetic field and experiences a force
• What causes the motor effect?(HT)


  Interaction between magnetic field around the wire and the permanent magnetic field
• How can you predict the direction of the force caused by motor effect?(HT)

  Fleming's left hand rule
• What is the function of the split ring commutator in a dc motor?(HT)

  Keeps motor spinning in the same direction (by changing direction of current every half turn)
• Name two ways you can you make a motor spin faster(HT)


  1.Increase current

  2.Increase strength of permanent magnetic field
• How can you make a motor spin in the reverse direction?(HT)

  1.reverse current

  2.reverse direction of permanent magnetic field