LC electricity resistance, semi conductors and other stuff!

  1. What is an emf?
    When a voltage is applied to a circuit
  2. What are the sources of an emf (electromotive force)
    • electrical mains
    • thermocouple
    • A cell
  3. What is ohm's law?
    the voltage is proportional to the current

    for a metallic conductor at a constant temperature, the current will be proportional to the voltage
  4. Draw the graph for current and voltage in metals.
    and how is current carried?
    graph directly proportional

    by electrons
  5. Draw the graph for current and voltage in filament bulbs.
    and how is current carried
    by electrons

    curved surface because at higher voltages the increased heat increases resistance, and limits the current
  6. Draw the graph for current and voltage in gases.
    and how is current carried
    By ions

    at higher voltages, no more ions can be created, limiting the current

    higher curve slant than f.b
  7. Draw the graph for current and voltage in vaccum.
    and how is current carried
    The cathode must be warmed.

    At higher voltages, electrons move across the vacuum

    graph: behind middle up curve slant to the right
  8. Draw the graph for current and voltage in electrolysis (inactive electrodes).
    and how is current carried
    by ions

    graph: directly proportional behind the middle
  9. Draw the graph for current and voltage in electrolysis (active electrodes).
    and how is current carried
    by ions

    directly proportional
  10. What is resistance?
    of an object within an electrical circuit is defined as the ratio of the voltage across it to the voltage flowing through it

    • R=V/I
    • measured in ohm's
  11. What varies resistance
    • the length (l)
    • the cross-sectional area (A)
    • the material from which the object is made (p)
  12. What is resistivity
    R=pl/A

    the resistance of a unit of that material
  13. What is the Wheatstone bridge used for?
Author
cat126
ID
351186
Card Set
LC electricity resistance, semi conductors and other stuff!
Description
revision questions
Updated