week 1

• Electricity and Magnetism


  Learning area
• Grade 12


  Grade level
• Identify the factors that affect the magnitude of the induced emf and the magnitude and direction of the induced current (Faraday's Law)
• Compare and contrast electrostatic electric field and non-electrostatic/ induced electric field
• Content/Core Content


  • Magnetic induction
  • Faraday's Law
  • Alternating current, LC circuits, and other applications of magnetic induction

  
• Introduction


  1. Electricity is related to magnetism

  2. Electricity produces magnetism

  3. Magnetism produces electricity

  4. Factors affecting induced emf and current (Faraday's Law)
• Electromagnetic Induction


  Discovered by Michael Faraday in the 1830s

  
• Faraday noticed that when he moved a permanent magnet in and out of a coil or a single loop of wire it induced an emf, and therefore a current was produced

  
• Faraday's Law of Electromagnetic Induction links electricity with magnetism

  
• Electromagnetic Induction by a Moving Magnet


  1. Magnet moved towards coil - galvanometer deflects one way

  2. Magnet held stationary - galvanometer returns to zero

  3. Magnet moved away from coil - galvanometer deflects opposite way

  4. Magnet moved back and forth - galvanometer deflects left/right
• Faraday's law of induction


  An electromotive force is induced by a change in the magnetic flux

  
• Induced EMF


  • Closing/opening switch induces current
  • Change in magnetic field creates current
• Factors affecting induced EMF


  • Increasing number of turns in coil
  • Increasing speed of relative motion between coil and magnet
  • Increasing strength of magnetic field
• Learning Task 1


  1. Download simulation

  2. Click field lines option

  3. Move magnet through loop of wire

  4. Change speed and reverse magnet
• What is observed on the galvanometer as the magnet goes through the loop of wire?
• How does reversing the magnet change the readings on the galvanometer?
• Observation of the galvanometer reading in terms of the amount of magnetic field lines going through the loop of wire
• The magnitude of the induced emf (electromotive force) depends on the speed of the bar magnet
• The mere presence of the bar magnets field induces an emf in the coil
• The direction of the induced emf depends on the speed of the magnet
• The direction of the induced depends on which pole (N/S) moves toward the coil
• Real-life applications of Faraday's Law


  1. induction stoves

  2. tape players

  3. metal detectors

  4. transformers

  
• Can you produce current in a wire with a magnet that is sitting still?
• What causes an increase in the induced EMF in a coil spinning in a magnetic field?
• What would happen if you move a bar magnet in and out of a coil of copper wire?
• Who formulated the principle behind electromagnetic induction?
• What basic principle enables ALL electric generators to operate?
• I was able to do/perform the task without any difficulty. The task helped me in understanding the target content/lesson.
• I was able to do/perform the task. It was quite challenging, but it still helped me in understanding the target content/lesson.
• I was not able to do/perform the task. It was extremely difficult. I need additional enrichment activities to be able to do/perform this task.