Magnetism and electromagnetism

• 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
• What does the closeness of magnetic field lines indicate?

  The strength of the magnetic field
• Where is the magnetic field strongest in a magnet?

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

  Always attractive
• What happens when two like poles of a magnet are near each other?

  They repel each other
• What does a compass contain?

  A tiny bar magnet
• 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
• What do permanent magnets do?

  Produce their own magnetic field
• What happens to induced magnets when the magnetic field is removed?

  They quickly lose their magnetism
• What is created around a wire when current flows through it?

  A magnetic field
• How is the magnetic field around a wire shaped?

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

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

  By increasing the current or decreasing distance
• What is a solenoid?

  A coil of wire
• How does wrapping a wire into a coil affect the magnetic field?

  It increases the strength of the magnetic field
• What happens to the magnetic field inside a solenoid?

  It is strong and uniform
• What is an electromagnet?

  A solenoid with an iron core
• What are the uses of electromagnets?

  Used in cranes and electric motors
• What is the motor effect?

  When a current-carrying wire moves in a magnetic field
• What must be the angle of a wire to experience full force in a magnetic field?

  90° to the magnetic field
• How does the force act in relation to the magnetic field and current?

  At right angles to both
• What increases the magnitude of the force on a conductor?

  Stronger magnetic field and more current
• What three factors affect the force on a conductor in a magnetic field?

  Magnetic flux density, current, length
• How can you find the direction of the force on a conductor?

  Using Fleming's left-hand rule
• What does Fleming's left-hand rule indicate?

  The direction of force, field, and current
• How can you reverse the direction of a motor?

  By reversing current or magnetic poles
• What happens in a loudspeaker when current reverses?

  The cone moves in the opposite direction
• What are the main components of a basic electric motor?

  • Coil of wire
  • Permanent magnet
  • Split-ring commutator
  • Current source
• How does a loudspeaker work?

  • Alternating current flows through a coil
  • Coil interacts with a permanent magnet
  • Force causes the cone to move
  • Variations in current create sound vibrations
• What is the relationship between current and magnetic fields in electromagnets?

  • Current creates a magnetic field
  • Magnetic field strength increases with current
  • Electromagnets can be turned on and off
• What is the significance of the split-ring commutator in motors?

  • Swaps contacts every half turn
  • Keeps the motor rotating in the same direction
  • Essential for continuous motion
• What is the role of the iron core in a solenoid?

  • Increases magnetic field strength
  • Becomes an induced magnet when current flows
  • Allows for a stronger electromagnet
• What is the function of a compass in relation to magnetic fields?

  • Indicates direction of magnetic fields
  • Points north due to Earth's magnetic field
  • Helps visualize magnetic field lines
• What are the characteristics of induced magnets?

  • Become magnets in a magnetic field
  • Lose magnetism when field is removed
  • Always attract permanent magnets
• What is the significance of the right-hand thumb rule?

  • Determines direction of magnetic field
  • Used for current-carrying wires
  • Helps visualize magnetic field orientation
• What is the relationship between magnetic flux density and force?

  • Force increases with magnetic flux density
  • Directly proportional to current and length
  • Essential for calculating force on conductors
• What direction should the current arrows be drawn?

  From positive to negative