magnetism <3

• Fleming's right-hand rule is used to determine the direction of force on a moving charge or current carrying conductor when placed in a magnetic field.
• A current carrying wire produces its own magnetic field around it, with the direction determined by Fleming's left hand rule.
• The magnetic field lines are always perpendicular to the direction of motion.
• Fleming's Left Hand rule?

  Thumb: Motion/direction

  Index - Field

  Middle - Current
• Fleming's Right Hand Rule?

  Thumb - Direction

  Index - Current
• How is the strength of the magnetic field of an electromagnet determined?

  Size of the current and distance of the wire
• Describe the inside of the solenoid of an electromagnet (hint: field lines)

  • Parallel
  • Evenly spaced
  • Straight
• What does the outside of a solenoid look like?

  The field lines look like a bar magnet's
• What way does the magnetic field go?

  North to south
• What is the magnetic field like?

  Strong and uniform
• Explain the use of electromagnets in scrapyards

  Used to pick up and deposit scrap metal from one place to another
• Explain the use of electromagnets in washing machine doors

  Used to lock washing machines during a cycle
• How do you increase the force acting upon a coil?

  • increase the current
  • increase the number of coils
  • increase the magnetic field strength
• How do loudspeakers work (in reference to the motor effect)?

  A moving-coil loudspeaker or set of headphones has an electromagnet inside a coil. A signal is passed to the loudspeaker in the form of a changing current.
• How can potential difference be induced in a conductor? Give two examples.

  • Conductor moving in the magnetic field
  • Change in magnetic field
• How do you induce greater potential difference? Give two ways.

  • More turns on the coil
  • Faster movement
• What causes the motor effect?

  When the field created by electric current interacts with the magnetic field that the wire is placed inside, which causes a force
• The motor effect in electric motors?

  Current will go up one side of the coil is flowing in the opposite direction to the current coming back down on the other side.
• What are the two types of current?

  • direct current (d.c.)
  • alternating current (a.c.)
• Properties of direct current + example(s)?

  • flows in one direction
  • example: batteries and cells
• Properties of alternating current?

  • repeatedly changes direction
  • examples: plug sockets
• How does a dynamo produce d.c.?

  In a dynamo, a coil of wire rotates + the magnet is fixed/stationary.

  1. Coil rotates and produces potential difference - goes one direction
  2. Split-ring commutator reverses direction every half-turn on the coil - this makes sure the current always moves in the same direction
  3. the potential difference is largest when the coil and the magnetic field are parallel
  4. potential difference = 0
  5. coil is perpendicular to the magnetic field
• How does an alternator generate alternate current?

  1. Rotating magnet + fixed coil of wire
  2. When the magnet rotates, the direction of the field alternates
  3. This produces alternating current