Electronic Technology


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  • Group Challenge: arrange yourselves into the electrical configuration of a doorbell. Parts needed: button/switch, battery, magnet, solenoid, gong, hammer/armature, spring & wires
  • STATOR "stays there" and ROTOR "rotates"
  • Review: Stator = permanent magnets, don't move Rotor = rotating armature (electromagnet, brush & split right commutator)
  • Review: Stator = permanent magnets, don't move Rotor = rotating armature (electromagnet, brush & split right commutator)
  • Brushes usually made of carbon - When the brushes reach the gap in the commutator, the circuit is broken, removing the magnetic field. - As it rotates further, the "other side" of the ring makes contact, switching the electromagnetic field of the rotor
  • What real motors look like.
  • Mary-go-round illustration: One person pushing a mary-go-round just once per rotation will result in a choppy spin that accelerates and slows according to when the push is given. However, if 8 people were positioned around the carousel to keep it going, the rotation would be much smoother.
  • A photograph of Michael Faraday , Thomas Henry Huxley , Charles Wheatstone, David Brewster and John Tyndall . Michael Faraday & Joseph Henry were the first to PROVE this connection
  • Electronic Technology

    1. 1. Electronic Technology
    2. 2. Magnetism Review <ul><li>What 3 common metals have the greatest magnetic permeability? </li></ul><ul><li>Name 3 examples of permanent magnets. (shape & material) </li></ul><ul><li>Name 2 types of temporary magnets. </li></ul><ul><li>Describe the domains of a magnet. </li></ul><ul><li>What is the only naturally-occurring magnet found in the Earth's crust? </li></ul><ul><li>What type of &quot;magnet&quot; is responsible for Earth's magnetic field? </li></ul><ul><li>Describe Earth's core. </li></ul><ul><li>iron, nickel & cobalt </li></ul><ul><li>ceramic bar, flexible & flat fridge magnet, neodymium disc </li></ul><ul><li>induced paper clip, electromagnet </li></ul><ul><li>aligned (same dir.) </li></ul><ul><li>lodestone </li></ul><ul><li>&quot;dynamo&quot; electromagnet </li></ul><ul><li>solid iron inner core, surrounded by swirling liquid iron </li></ul>
    3. 3. Magnetism Review <ul><li>What word is used to describe Earth's magnetic pole's angle of variation from the geographic poles? </li></ul><ul><li>Describe the shape and polarity of Earth's magnetosphere. </li></ul><ul><li>True or False: The strength and location of Earth's magnetic poles constantly change; there's even evidence they've been reversed in the past. </li></ul><ul><li>Why is the magnetosphere important? </li></ul><ul><li>What do magnetic storms do? </li></ul><ul><li>Name 5 devices that use electromagnets . </li></ul><ul><li>declination </li></ul><ul><li>geographic north is magnetic south, sun-side is &quot;squashed&quot; </li></ul><ul><li>true </li></ul><ul><li>solar wind protection </li></ul><ul><li>heat/distort atmosphere </li></ul><ul><li>MRI, hairdryer, car door locks, speaker, maglev train, crane, electric toothbrush, toys, etc. </li></ul>
    4. 4. Magnetism Review <ul><li>Every wire carrying electricity has a weak around it. </li></ul><ul><li>What does the &quot;right-hand rule&quot; show us? </li></ul><ul><li>How does looping a wire carrying electricity affect the magnetic field around it? </li></ul><ul><li>What is a coil of current-carrying wire called? </li></ul><ul><li>What is created by running electric current around a magnetic material? </li></ul><ul><li>How does reversing the flow of electrons in a current affect the magnetic field? </li></ul><ul><li>What could you adjust to make a stronger electromagnet? </li></ul><ul><li>magnetic field </li></ul><ul><li>direction of current & flux </li></ul><ul><li>strengthens it </li></ul><ul><li>solenoid </li></ul><ul><li>electromagnet </li></ul><ul><li>reverses poles </li></ul><ul><li>more current, more/neater coils, better core material, lower temperature </li></ul>
    5. 5. Electric Motors <ul><li>An electric motor converts electricity into mechanical motion. </li></ul><ul><ul><li>Most electric motors are rotary, producing rotational movement (spin, like a fan or turn of a wheel). </li></ul></ul><ul><li>Stator: the stationary part </li></ul><ul><ul><li>usually a permanent magnet </li></ul></ul><ul><ul><li>surrounds the rotor </li></ul></ul><ul><li>Rotor : the rotating part </li></ul><ul><ul><li>usually on the inside </li></ul></ul><ul><ul><li>contains an electromagnet attached to a frame called the armature </li></ul></ul>
    6. 6. Creating Motion from Electricity <ul><li>Permanent magnets attract opposite poles of the electromagnet inside, causing it to rotate </li></ul><ul><li>Turn the electromagnet off momentarily & momentum will keep it turning </li></ul><ul><li>Then switch the poles of the electromagnet and the stationary magnets pull again, continuing the motion </li></ul>Electromagnet (coils not pictured) N S
    7. 7. Motion from Electricity N S N S 3. Reversed poles of electromagnet, continue motion 2. Momentum keeps it turning when switched off 1. Stator magnets attract opposite poles of the electromagnet N S
    8. 8. Rotor Assembly <ul><li>Armature (inner rotating part) </li></ul><ul><ul><li>battery supplies current </li></ul></ul><ul><ul><li>two brushes (connectors) </li></ul></ul><ul><ul><li>commutator </li></ul></ul><ul><ul><ul><li>gaps stop current flow </li></ul></ul></ul><ul><ul><ul><li>rotation switches poles </li></ul></ul></ul><ul><ul><li>solenoid </li></ul></ul><ul><ul><ul><li>(many coils) </li></ul></ul></ul><ul><ul><li>solid iron core </li></ul></ul><ul><ul><ul><li>(not pictured) </li></ul></ul></ul>electro-magnet N S split ring commutator brush
    9. 9. The Simple DC Motor <ul><li>The force applied to the armature by the stationary magnetic field which causes it to rotate is called torque . </li></ul>
    10. 11. Multiple-Electromagnet Motors <ul><li>Most motors have more than one magnet in the armature to assure smooth rotation. </li></ul>
    11. 12. Pioneering scientists wondered... <ul><li>If electrical currents can produce a magnetic field, can magnetic fields also produce an electrical current? </li></ul><ul><li>What do you think? </li></ul>If moving electrons produce a &quot;push&quot; (magnetic field) then that same &quot;push&quot; applied to a wire should cause electrons to move!
    12. 13. <ul><li>How is this diagram different than a motor? </li></ul>A hand crank replaces the battery.
    13. 14. Creating Electricity from Magnets <ul><li>PhET Simulation </li></ul><ul><li>Pickup Coil tab </li></ul><ul><ul><li>Dots moving in the wire represent electric current </li></ul></ul><ul><ul><ul><li>the faster they travel, the greater the current </li></ul></ul></ul><ul><ul><li>Reading the Field Meter </li></ul></ul><ul><ul><ul><li>B (top measurement) gives the overall field strength. </li></ul></ul></ul><ul><ul><ul><li>G stands for Gauss, the SI unit of magnetic field strength </li></ul></ul></ul><ul><ul><ul><li>Bx & By give coordinates to graph the flux lines </li></ul></ul></ul><ul><ul><ul><li>Ө gives the angle (in degrees) of the magnetic lines of force </li></ul></ul></ul><ul><ul><li>Yellow lines around bulb show electricity is generated </li></ul></ul><ul><ul><ul><li>longer lines indicate more current </li></ul></ul></ul>
    14. 15. Electromagnetic Induction <ul><li>A changing magnetic field causes current to flow in a conductor </li></ul><ul><ul><li>Mechanical energy (KE - the energy of motion) is converted into electricity </li></ul></ul><ul><li>Current flows ONLY when the magnetic field changes </li></ul><ul><ul><li>magnet moves </li></ul></ul><ul><ul><ul><li>permanent magnet </li></ul></ul></ul><ul><ul><li>poles are reversed </li></ul></ul><ul><ul><ul><li>electromagnet </li></ul></ul></ul>
    15. 16. Electric Generators <ul><li>A generator is a device which produces current by electromagnetic induction. </li></ul><ul><ul><li>magnetic forces push electrons through a wire </li></ul></ul><ul><ul><li>opposite process of a motor </li></ul></ul><ul><ul><li>requires external energy source </li></ul></ul>
    16. 17. Hydroelectric Generator Nuclear Power Generator Human-Power Generator Wind Turbine Generator Steam Turbine Generator