P4.1

• what are the ends of a magnet called?

  poles
• the law of magnetism states that 2 of the _____ poles repel each other

  same
• the law of magnetism states that two _________ poles attract each other

  opposite
• are magnetic materials attracted to magnets?

  yes
• are non-magnetic materials attracted to magnets?

  no
• examples of magnetic materials

  iron, cobalt, nickel and steel
• why is steel magnetic?

  it is an alloy, which contains iron
• magnetic materials will always be attracted to the magnet, regardless of which pole is held close to it.
• how can we test whether a material is magnetic?

  1. bring it close to a known magnet
  2. if it can be repelled, the material itself is a magnet
  3. if it can only be attracted, then it is a magnetic material
• what are the 2 types of magnets?

  permanent and induced
• what are permanent magnets made of?

  magnetic materials e.g. steel
• what is the key feature of a permanent magnet?

  it produces its own magnetic field and will not lose its magnetism
• how are induced magnets created?

  when a magnetic material is placed in a magnetic field, the material can be temporarily turned into a magnet
• magnetic materials will always be attracted to a permanent magnet. this means that

  • the end of the material closest to the magnet will have the opposite pole that it is next to.
• what happens when a magnetic material is removed from the magnetic field?

  it loses all/most of its magnetism quickly
• what is a magnetic field?

  the region around a magnet where a force acts on another magnet / magnetic material
• what do you use to show the direction of the magnetic field?

  arrows
• how is the strength of a magnetic field shown?

  by the spacing of the magnetic field lines
• if the magnetic field lines are close together, the magnetic field is?

  strong
• if the magnetic field lines are far apart, the magnetic field is?

  weak
• what is the direction of the field lines?

  always go from north to south
• where is the magnetic field the strongest?

  poles
• what type of magnetic field is produced in the gaps between opposite poles?

  uniform
• how can we prove that the core of the earth is magnetic?

  in the absence of any magnet or magnetic materials, a magnetic compass will always point north.
• when is a magnetic field produced around the wire?

  When current flows
• how can we work out the direction of the magnetic field?

  using the right-hand thumb rule

  • point the thumb along the direction of the current
  • the other fingers curl around to give the direction of the field
• what does a circle with a dot show?

  current is flowing out of the plane
• what does a circle with a cross show?

  current flowing into the plane
• what factors affect the strength of a magnetic field?

  the size of the current and the distance from the long straight conductor (e.g. a wire)
• what is a solenoid?

  a wire coiled up into a spiral shape
• how can we increase the strength of the magnetic field around a solenoid?

  1. increase the size of the current flowing through the wire
  2. increase the number of coils
  3. add an iron core through the centre of the coils