9 LESSON_Q2

• This module is based on DepEd's Most Essential Learning Competency (MELC) Number 6 for Science 10, Quarter 2
• Learning Competency


  Explain the operation of a simple electric motor and generator (S10FE-IIj-54)
• Lessons in this module

  • Lesson 1 - Interaction of Electricity and Magnetism
  • Lesson 2 - Electric Motor
  • Lesson 3 - Generator
• Specific learning objectives


  • Review basic concepts of electricity and magnetism
  • Describe how electricity induces magnetism
  • Describe how magnets are used to generate electricity
  • Explain how electric motors operate
  • Explain how generators work
• To determine the direction of the magnetic force we use the right-hand rule
• Right-hand rule


  If the direction of the magnetic field is pointed by the 4 fingers and the flow of charge is directed by the thumb, then the magnetic force should be where the palm is facing towards
• Output energy of an electric motor

  Mechanical energy
• Faraday's law


  The faster the change in magnetic flux is, the larger the electromotive force or voltage produced is
• Scientist who discovered that electricity can produce magnetism

  Hans Christian Oersted
• Lenz's law


  The induced magnetic field will always be opposed to the changing magnetic field that created it
• Induced voltage


  Develops in a coil that "feels" a changing magnetic field
• AC generator


  Designed to produce electricity that oscillates between the positive and negative directions
• Magnetic field


  Generated when a charge moves inside a conducting wire
• Commutator


  Used in an AC generator to ensure that the same wire is connected to same side of the coil as it rotates
• Magnetic force


  Exerted on a charged particle that crosses the magnetic field of another magnet
• Electromagnetic induction


  Concept demonstrated by Michael Faraday and Joseph Henry
• Direction of magnetic force

  To the left
• Commutator


  Used in a simple electric motor to ensure that the current in the coil reverses every half a turn
• The north pole of a magnet will attract the south pole of another magnet
• Same poles of two magnets will repel each other
• Direct current (DC)


  A type of current that flows only in one direction
• Alternating current (AC)


  A current that flows in a circuit such that it oscillates the electrons back and forth
• Electric circuit


  A complete and closed path around which a circulating electric current can flow
• When electricity flows through the wire, the iron nail becomes an electromagnet and can attract metal paper clips
• When the electricity is cut off, the nail loses its magnetism and can no longer attract the paper clips
• This shows the relationship between electricity and magnetism
• When a charge such as an electron moves, it creates a magnetic field
• A coil or solenoid with electricity flowing through it becomes an electromagnet
• Electromagnetic induction is the concept that a changing magnetic field can induce electricity
• Michael Faraday and Joseph Henry demonstrated experimental evidence for electromagnetic induction
• A changing magnetic field is required to induce electricity in a wire, coil or solenoid
• When a charged particle crosses the magnetic field of a stationary magnet, it is subjected to a magnetic force
• A stationary charged particle "feels" a changing magnetic field when a magnet moves towards it
• Relative perpendicular motion between a charge and a magnetic field generates a magnetic force, regardless of which one is moving
• A changing magnetic field creates an electric field, and a changing electric field creates a magnetic field
• This interaction between changing electric and magnetic fields is what enables the generation of electromagnetic waves
• In an incandescent bulb, the vibrating electrons produce an electromagnetic wave corresponding to visible light
• Hans Christian Oersted discovered that electricity can create magnetism
• Electromagnet


  A device that becomes a magnet whenever electricity is allowed to flow through it
• Magnetic force


  The force exerted on a charged particle that crosses the magnetic field of another magnet