magnets and magnetic fields

• What happens when like poles of magnets are brought together?

  They repel each other
• What occurs when opposite poles of magnets are brought together?

  They attract each other
• What type of forces are attraction and repulsion between magnetic poles?

  Non-contact forces
• What does a permanent magnet produce?

  Its own magnetic field
• How do two permanent magnets interact when brought close together?

  They can attract or repel each other
• What is an induced magnet?

  An object that becomes a magnet in a field
• What happens to an induced magnet when the permanent magnet is removed?

  It loses most or all of its magnetism
• What type of force does induced magnetism always cause?

  A force of attraction
• What are the four types of magnetic materials?

  • Iron
  • Steel (an alloy of iron)
  • Cobalt
  • Nickel
• What is a magnetic field?

  A region where a force acts on magnets
• What happens when magnetic materials are placed in a magnetic field?

  They experience a force of attraction
• How does the strength of a magnetic field change with distance from the magnet?

  It decreases as distance increases
• Where is the magnetic field strongest on a magnet?

  At the poles of the magnet
• What does a magnetic compass contain?

  A small bar magnet
• How do we plot a magnetic field using a compass?

  By drawing crosses at compass north poles
• In which direction do magnetic field lines point?

  From north to south
• What indicates the strongest part of a magnetic field?

  Where the lines are closest together
• What does a compass needle point to when away from magnets?

  North-South direction
• Why does a compass needle point north?

  Because of Earth's magnetic field
• What happens when we close the switch in a circuit?

  An electric current flows around the circuit
• What is conventional current?

  Flow from positive to negative
• What is produced around a wire when current flows through it?

  A magnetic field
• How can we prove the existence of a magnetic field around a wire?

  Using a compass to observe deflection
• What factors affect the strength of the magnetic field around a wire?

  Size of current and distance from wire
• What happens to the magnetic field if we change the direction of the current?

  The direction of the magnetic field changes
• How do we determine the direction of the magnetic field using the Right Hand Rule?

  Thumb points current direction, fingers field direction
• What is a solenoid?

  A wire coiled into a loop
• What happens when current is turned on in a solenoid?

  A strong and uniform magnetic field is produced
• What are three ways to increase the strength of a magnetic field produced by a solenoid?

  Increase current, number of turns, add iron core
• What is an electromagnet?

  A solenoid with an iron core
• What is a key advantage of electromagnets?

  We can turn them on and off
• How can we change the strength of an electromagnet's magnetic field?

  By changing the current
• What happens when like poles of magnets are brought together?

  They repel each other.
• What occurs when opposite poles of magnets are brought together?

  They attract each other.
• What type of forces are attraction and repulsion between magnetic poles?

  Non-contact forces.
• What does a permanent magnet produce?

  Its own magnetic field.
• How do two permanent magnets interact when brought close together?

  They can attract or repel each other.
• What is an induced magnet?

  An object that becomes a magnet in a magnetic field.
• What happens to induced magnets when the permanent magnet is removed?

  They lose most or all of their magnetism quickly.
• What type of force does induced magnetism always cause?

  A force of attraction.