magnetism + motor effect notes

• what is a magnet

  a magnet is any material that creates a magnetic field and also has to poles a north and a south
• how are magnet fields represented and show

  magnetic fields are represented by field lines
• how would you draw a magnetic lines and advantages

  • field lines (outside lines) always go from north to south meanwhile regular lines conform in the south and dispersence from the north.
  • Advanatges is it shows the strength of the magnetic field and also the direction of the magnetic field as more dense(closer lines) show a stronger magnetic field
  • pointing in south pointing out north

  
• how would you draw a magnetic field of two poles that are the sasme

  repulsion

  
• what is a uniform magnetic field

  • a magnetic field of two uniform magnets of opposite ends are attracted to each other and the magnetic field is the same everywhere I'm the poles
• How to draw a uni form field magnet

  A opposite ends of two magnets

  At least 3 field lines parallel to each other

  
• what is the difference between a magnet and a magentic material

  • a magnet is any object that produces a mangnetic field while a magentic material is any material that is influenced by a magnet
• what are some magnetic materials

  nickle colbalt steel iron
• What is the difference between an induced and a permanent magnet

  • an induced magnet is a material that creates it's own magnetic field when exposed to a magnet while a permanent magnet creates it's own magnetic field all the time
• what is the difference between magnetically soft and hard materials

  • a magentically soft material is an induced magnet which loses it's magnetism very quickly
  • a magneticvally hard material is a material that loses it's magnetism more slowly and is used to create a permanent magnet
• How do we know the earths core is magentic

  • In the absence of a magnet material a compass always points north
  • on earth the north arrow on a compass will always points to the north pole due to the earth acting like a bar magnet and the north pole is actual a magnetic south pole as the magnetic field lines come out of the pole
  • north attracted to south
• what is formed when current flows through a wire

  • a magnetic field with no north and south where the straight line is made up of concentric circles
• How does the magnetic field produced through a wire relate with distance

  • as the distance increases so the magentic field decreases and concentratic circles are made further away
• what is a solenoid

  • a solenoid is a coiled up piece of wire that Carries a current.The magnetic field inside a solenoid formed by the coils add together to create a strong uniform field inside
  • out the magnetic field the field lines of the concentric circles overlap with each other
• How can you increase the magnet field in a solenoid

  • increase the current
  • increase the number of coils
  • add a soft iron corewhich becomes an induced magnets when current is flown through the coils and lead to a stronger field overall
• describe how a student can use a compass to find a magentic field

  • place a magnet on the paper
  • different places on the paper marking the direction
  • join up the direction of the field lines
• Using paper clips a bar magentic and iron how can someone show that an induced magent

  • place the iron near the magent to induce it and become a magentic field
  • watch paper clips be attracted to the iron
  • remove iron from magents and magents don;t stick to the iron anyore
• what are some uses of magnetic materials

  • doorbells
  • fridge doors
  • speakers and microphones
• What is the motor effect

  • the motor effect is when a current carrying wire is placed in a magnetic field and experiences a fprce
  • the wire had to be perpendicular to the field and if it runs in the same direction no force is felt at all
• How does a split ring commutator work

  • swaps the positive and negative terminals every half turn
  • causes current to change every half turn
  • causes the forces acting on the wire to go in the same direction
  • causes the coil to continuosly rotate in the same direction
• How does a motor work


  • forces act on a current driven coil of wire in a magnetic field (motor effect)
  • forces on each terminal act on opposite directions
  • split ring commutator is used so the motor rotates in the same direction
• How to increase the speed of an electric motor


  • increase current
  • increase magnetic fleux density
  • add more coils to the wire