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Electromagnetism, Electric Motor, Generator | Grade 10 Science DepEd MELC Quarter 2 Module 6

Introduction to Magnets and Magnetism

  • Compass Discovery

    • Originated from the Chinese in the 12th century

    • First built to aid navigation using magnetism

Understanding Magnetism

  • Definition

    • Magnetism: Force exerted by magnets attracting or repelling each other

    • Early discovery of lodestone, a naturally magnetized mineral

  • Magnetic Properties

    • Magnet: A substance that generates a magnetic field

    • Ferromagnetic materials: Substances like iron, steel, nickel, and cobalt, strongly attracted to magnets

Types of Magnets

  • Natural and Artificial Magnets

    • Natural Magnets

      • Lodestones are examples of permanent magnets which do not lose magnetic power

    • Artificial Magnets

      • Made through induced magnetism (stroking ferromagnetic materials with a magnet)

      • Types

        • Temporary Magnets: Magnetism can be turned on/off

        • Permanent Magnets: Magnetic strength never fades

          • Examples: Refrigerator magnets, neodymium magnets (strongest available)

Properties of Magnets

  • Magnetic Poles

    • Every magnet has a north pole and a south pole

    • Opposite poles attract; like poles repel

  • Magnetizing Elements

    • Elements: Iron, nickel, cobalt, aluminum, gadolinium, dysprosium

    • Permanent magnets require an alloy, typically steel (carbon and iron)

Applications of Magnets

  • Used in navigational compasses for ships, which float on alcohol and point north

  • Common in household items: electric motors, speakers, televisions, and refrigerator doors

Magnetic Field Dynamics

  • Field Strength and Proximity

    • Magnetic force strengthens as magnets are brought closer together

    • Force weakens with distance until no force is felt

  • Magnetic Fields

    • Space around a magnet exerting influence on objects

    • Magnetic field lines show direction and concentration of strength around magnets

      • Example: Horseshoe magnets concentrate force between poles, enabling heavier lifting compared to bar magnets

Historical Discoveries in Magnetism

  • Michael Faraday's Contributions

    • Described magnetic fields with lines of force that never overlap

    • Discovered electromagnetism linking electric current with magnetic fields through Ørsted’s observations

Electromagnetism Principles

  • Electromagnet

    • Magnet that can be turned on/off, typically a solenoid with a core

    • Strength increased by turning more coils

  • Electromagnetic Induction

    • Process by which a moving wire generates electric current in a magnetic field (discovered by Faraday and Joseph Henry)

  • Coils Interaction

    • Primary coil induces current in secondary coil, influenced by proximity and properties of the coils

    • Current direction changes based on magnetic field changes

Fleming’s Right-Hand Rule

  • Guides direction of current, field, and force

    • Thumb: Direction of force

    • Index Finger: Direction of magnetic field

    • Middle Finger: Direction of current

Generators and Electric Motors

  • Generator Principles

    • Converts mechanical energy to electrical energy using electromagnetic induction

    • Alternating current (AC) vs. Direct current (DC) generators based on current direction continuity

  • Electric Motors

    • Converts electrical energy back to mechanical through electromagnetism

    • Operate on alternating currents which reverse polarity to enable movement

Summary of Key Concepts

  • Magnetism is a fundamental force related to materials' magnetic properties

  • Magnets are classified into natural and artificial, with temporary and permanent types in artificial magnets

  • Key concepts like electromagnetic induction facilitate vital applications in generators and motors, impacting everyday technology.