magnetism

• magnetism a non-contact force.
• what is an example of a magnetic material that doesn't always act like a magnet?

  iron
• when are magnetic materials (like iron) not magnetic?

  a normal piece of iron won't attract or repel another piece of iron, but will attract to a magnet if close enough to it.
• permanent magnets are always magnetic, even when they are not near other magnets. They produce their own magnetic field.
• what happens when permanet magnets induce temporary poles in the magnetic material?

  these align so that the magnetic material is attracted to the permanent magnet.
• what will happen the a north pole of the magnet is next the magnetic material

  a south pole will be induced in the part of the material closest to the magnet.
• what is induced magnetism?

  the temporary creation of magnetic poles in magnetic materials close to a magnet. It lasts as long as the magnet is near.
• how can you tell if an object is magnetic?

  it will attract magnetic materials and will repel one pole of another magnet.
• there is always an attractive force between an induced magnet (or magnetic material) and a permanent magnet.
• what does magnetism describe?

  the ability of magnets to attract or repel other magnets without touching them.
• what does the strength of a magnetic field depend on?

  the distance from the magnet. The magnetic field is always strongest at the poles.
• where is the magnetic field always the strongest?

  at the poles.
• what does every magnet create around itself?

  a magnetic field
• what is a magnetic field?

  the area around a magnet where another magnet or magnetic material (iron, steel, nickel, cobalt) feels a force.
• what are magnetic forces (forces between magnets) caused by?

  invisible magnetic fields.
• what does a magnetic compass contain?

  a small bar magnet. The needle of the compass points in the direction of earth's magnetic field. This shows that the earth's core is magnetic.
• what do the arrows on magnetic field lines show?

  the direction of a magnetic field. The arrows always point from the north pole of the magnet to the south pole.
• what is the strength of the magnetic field at any point indicated by?

  the density of the field lines at that point.
• why is the earth's N-pole actually a magnetic south pole?

  the N-pole of a magnetic compass will point towards the magnetic north pole.
• how does earth's core behave like a bar magnet?

  if a compass is mounted vertically (a dipping compass) it shows that earth's magnetic field enters the earth at different angles in different places.
• what can be used to detect earth's magnetic field?

  a compass
• how can a solenoid be made into an electromagnet?

  the solenoid should be wrapped around a core. For a strong electromagnet, the core should be made of iron.