Magnetism & motor effect

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

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

  They attract each other.

  
• Which materials are typically magnetic?

  Cobalt, Steel, Iron, and Nickel.
• What are permanent magnets and their uses?

  • Always magnetic and have fixed poles
  • Used in:
  • Speakers
  • Compasses
  • Electric generators
• What are induced magnets and how are they created?

  • Materials that become magnetic when induced
  • Created by:
  • Stroking with a permanent magnet
  • Aligning domains in the material

  
• What happens to induced magnets after time or a knock?

  The domains move into random positions, causing magnetism to be lost.

  
• What is the direction of magnetic field lines?

  • Point from North to South
  • Direction always points to the south pole and away from the north pole

  
• What do plotting compasses show?

  The direction and shape of a magnetic field at a given point.
• How does Earth's core contribute to magnetism?

  • The core is magnetic and creates a large magnetic field around Earth
  • A freely suspended compass aligns with Earth's field lines and points North
• Why is Earth's magnetic pole in the north actually a magnetic South Pole?

  Because like poles repel, so the north pole of a compass aligns with a magnetic south pole.
• What does current produce around a wire?

  A magnetic field.
• What is the "right hand rule" in relation to current and magnetic fields?

  • It dictates the direction of the magnetic field produced by the current
  • Current direction is perpendicular to the magnetic field direction
• How does magnetic field strength depend on current size?

  Greater current results in a stronger magnetic field.
• How does magnetic field strength vary with distance from the conductor?

  Greater distance from the wire results in a weaker magnetic field.

  
• What is the shape of the magnetic field produced by a solenoid?

  • Similar to a bar magnet
  • Coiling the wire aligns the field to form a uniform field along the center

  
• What effect does having an iron core in a solenoid have?

  It increases the strength of the magnetic field.
• What factors affect the strength of a magnetic field in a solenoid?

  • Size of current
  • Length of the solenoid
  • Cross-sectional area
  • Number of turns (coils)
  • Using a soft iron core
• What happens when a wire carrying current is near a magnet?

  The current produces a magnetic field that interacts with the magnet's field.

  
• What is the nature of the force experienced by a wire near a magnet?

  The force is equal and opposite to the force felt on the magnet.

  
• How do magnetic fields around a wire and between two magnets differ?

  • The magnetic field around a wire is circular
  • The magnetic field between two magnets is straight

  
• How is the force on a wire visualized when it interacts with magnetic fields?

  The wire is pushed away from the field between the poles at right angles to both the current and field direction.

  
• What is Fleming's Left Hand Rule used for?

  • To determine the unknown factor among force, magnetic field, and current
  • Each component is at 90° to the others
• What is the formula for force in terms of magnetic flux density, current, and length?

  $F =$$BIL$
• In what unit is magnetic flux density measured?

  Tesla [T].
• How does a motor operate using magnetic fields?

  • A coil of wire is placed between two permanent magnets
  • Current flows through the wire, interacting with the magnetic field
  • Causes one side of the coil to move down and the other side to move up, resulting in rotation

  
• How can the direction of movement in a motor be verified?

  • Use the Left Hand Rule to determine which side moves up or down
• What happens when current flows through a wire?

  A magnetic field is generated around it.
• What factors affect the strength of the magnetic field generated by a current-carrying wire?

  The strength depends on the magnitude of the current and the distance from the wire.
• What is an electric motor?

  A current-carrying coil of wire in a magnetic field.
• How does a current-carrying coil in a magnetic field cause rotation?

  The two sides of the coil that are perpendicular to the magnetic field experience forces in opposite directions.
• What is an electromagnet?

  A solenoid with an iron core.
• What occurs when a current-carrying wire is placed perpendicular to a magnetic field?

  A force is exerted on the wire.
• What is the relationship between the force on a wire and the magnetic flux density?

  The force is proportional to the magnetic flux density of the field, the current, and the length of the wire.
• What is Fleming’s Left-Hand Rule used for?

  To determine the orientation of the force, current, and magnetic field in a current-carrying wire.
• What is an induced magnet?

  A material that becomes a magnet when placed in an existing magnetic field but loses its magnetism quickly once removed.
• What type of forces do induced magnets produce?

  Induced magnetism always produces attractive forces.
• What happens when like magnetic poles are brought near each other?

  They repel each other.
• What is a magnetic field?

  The region around a magnet in which another magnet or magnetic material will experience a force.
• What do magnetic field lines represent?

  The strength and direction of a magnetic field.
• How do magnetic field lines indicate the magnitude of the field?

  Their concentration represents the magnitude of the field.