P7- Magnetism and Electromagnetism

• What are the two types of poles in magnets?

  North and South Poles
• What happens when same 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 are permanent magnets?

  Always magnetic, always have poles
• What are induced magnets?

  Materials that are magnetic but lack fixed poles
• How can induced magnets be made into temporary magnets?

  By stroking them with a permanent magnet
• What happens when domains in a material are aligned?

  A temporary magnet is created
• Which materials can become induced magnets?

  Iron, Nickel, Cobalt
• What do magnetic field lines indicate?

  They point from North to South

  
• How does the strength of a magnetic field change with distance?

  It decreases with distance from the magnet
• What direction do magnetic field lines point?

  Toward the south pole and away from the north pole
• How can plotting compasses be used in studying magnetic fields?

  They show the direction of the magnetic field
• What is the Earth's core's role in magnetism?

  It creates a large magnetic field around Earth
• Why does a compass point north?

  It aligns with Earth's magnetic field lines
• Where does the compass point instead of the geographic North Pole?

  It points over North Canada
• What is the nature of Earth's magnetic pole above Canada?

  It is a magnetic South Pole
• What does the current produce around a wire?

  A magnetic field
• How is the direction of the magnetic field around a wire determined?

  By the right hand grip rule

  
• What happens to the strength of the magnetic field with greater current?

  It becomes stronger
• How does distance from the wire affect the magnetic field?

  Greater distance results in a weaker field
• What shape does the magnetic field of a solenoid resemble?

  It is similar to a bar magnet

  
• How does coiling the wire in a solenoid affect the magnetic effect?

  It enhances the magnetic effect
• What increases the strength of a solenoid?

  Having an iron core in the center
• What factors affect the strength of a solenoid's magnetic field?

  • Size of current
  • Length of solenoid
  • Cross-sectional area
  • Number of turns (coils)
  • Using a soft iron core
• What is the motor effect?

  Interaction between two magnets causing force
• How do a magnet and a wire interact?

  They exert a force due to their magnetic fields
• What is the shape of the magnetic field around a wire?

  It is circular
• How does the force on a wire relate to the magnetic field?

  It is at right angles to both
• What does Fleming’s Left Hand Rule help determine?

  The unknown factor among force, current, and field
• What does the symbol F represent in Fleming's Left Hand Rule?

  Force
• What does the symbol B represent in Fleming's Left Hand Rule?

  Magnetic Flux Density
• What is induced when there is relative movement between a conductor and a magnetic field?

  A potential difference across the conductor
• What happens if the magnetic field changes during induction?

  A current flows if there's a complete circuit
• What does the movement of the wire in a generator cause?

  It cuts through the magnetic field
• What is produced when the coil of wire is connected to a complete circuit in a generator?

  An alternating current (AC)
• What does a split ring commutator do in a dynamo?

  Reverses the current each half-rotation
• What type of current does a dynamo produce?

  Direct current (DC)
• What happens in a transformer when AC is in the first coil?

  It creates a changing magnetic field
• What does a step-up transformer do?

  Increases voltage with more coils on secondary
• What does a step-down transformer do?

  Decreases voltage with fewer coils on secondary