PHYSICS: MAGNETISM AND ELECTROMAGNETISM

• What are the two poles of a magnet?

  North and south poles
• What do all magnets produce?

  A magnetic field
• What materials experience a force in a magnetic field?

  Magnetic materials like iron and nickel
• How can you visualize a magnetic field?

  By drawing magnetic field lines
• In which direction do magnetic field lines go?

  From north to south
• What does the spacing of magnetic field lines indicate?

  The strength of the magnetic field
• Where is the magnetic field strongest?

  At the poles of a magnet
• What type of force exists between a magnet and magnetic material?

  Always attractive
• What is inside a compass?

  A tiny bar magnet
• What happens when two like poles are brought together?

  They repel each other
• Why does a compass point north when not near a magnet?

  Because of Earth's magnetic field
• What are the two types of magnets?

  Permanent and induced magnets
• How do induced magnets behave in a magnetic field?

  They turn into magnets
• What happens to induced magnets when the magnetic field is removed?

  They quickly lose their magnetism
• What creates a magnetic field around a moving charge?

  The movement of the charge itself
• How is the magnetic field around a wire shaped?

  Concentric circles perpendicular to the wire
• What happens to the magnetic field if the current direction changes?

  The direction of the magnetic field changes
• How can you increase the strength of the magnetic field around a wire?

  By increasing the current or using a coil
• What is a solenoid?

  A coil of wire
• What happens to the magnetic field when wire is wrapped into a coil?

  The magnetic field is increased
• What is the generator effect related to?

  Inducing current in a coil
• What happens as a coil rotates in a generator?

  A current is induced in the coil
• What is the effect of placing an iron core inside a solenoid?

  It increases the magnetic field strength
• What is an electromagnet?

  A solenoid with an iron core
• How often does the current change direction in a generator?

  Every half turn
• Why are electromagnets useful?

  They can be switched on and off easily
• What do commutator contacts do in a generator?

  They don't swap every half turn
• What type of current do generators produce?

  Alternating current
• How do electromagnets work in cranes?

  They attract and pick up magnetic materials
• What is the main difference between dynamos and alternators?

  Dynamos have a split-ring commutator
• What is the motor effect?

  Movement caused by a current in a magnetic field
• What does a split-ring commutator do in a dynamo?

  Swaps connection every half turn
• At what angle does a wire experience the full force in a magnetic field?

  At 90° to the magnetic field
• How does a dynamo keep current flowing?

  By swapping connections every half turn
• What happens if a wire is parallel to the magnetic field?

  It won't experience any force
• What do oscilloscopes display regarding generated potential difference?

  Changes over time
• How does the line appear on an oscilloscope for AC?

  It goes up and down, crossing the axis
• How can you demonstrate the motor effect?

  By applying current to rails in a magnet
• How does the line appear on an oscilloscope for DC?

  It stays above the axis
• What increases the magnitude of the force on a conductor?

  Stronger magnetic field and more current