Physics Test

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oaboss
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247890
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Physics Test
Updated:
2013-11-20 08:45:15
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Physics
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Test 3
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  1. The magnetic field of a bar magnet is  similar to that produced by____?
    A current carrying wire shaped like a coil
  2. A device that converts electric energy into mechanical energy is a _____?
    Motor
  3. T or F : For a simple magnet, like poles attract.
    False
  4. T or F: A magnet at rest next to or inside a wire loop will cause a deflection of the ammerte's needle in Faraday's 1831 experiment
    False
  5. In practice, most transmission lines lose _____ of the generated power as heat.
    10%
  6. To change voltage to a higher or lower value, a _____ is used.
    Transformer
  7. The voltage induced in the 2nd coil of a transformer is dependent on?
    The number of turns in that coil vs the 1st coil.
  8. Most newly installed  transmission lines today are at a voltage of ____.
    up to 765 kV
  9. Wind-energy capacity has grown in the U.S. by ____ over the past 5 yrs.
    400%
  10. By a process called doping impurities are added to the silicon to change its properties and make it a better conductor. If a small amount of phosphorus is added to silicon, there will be ___ electrons in the crystal, producing an ____ semiconductor.
    • Extra electrons,
    • n-type (negative) semiconductor
  11. Einstein explained the photoelectric effect by describing light as a particle rather than a wave. The energy of each light particle, a photon, depends on its ______ only.
    Frequency
  12. Although conversion efficiencies can be over 30, typical efficiencies are _____ for a pv cell
    10-15%
  13. T or F: When light shines on the negative plate in figure 12.3, electrons are emitted with an amount of kinetic energy inversely proportional to the wavelength of the incident light.
    True
  14. The US produces about 7% of its electricity today from hydropower.
    7%
  15. About _____% of the worlds electricity is produced by hydropower.
    21%
  16. T or F: Some Micro-hydro turbines are as small as 200W and are cheaper than a PV unit of the same size, with greater availability.
    True
  17. What type of a turbine is a Pelton turbine?
    Impulse
  18. Concentrated Solar trough systems work by using parabolic reflectors in a trough configuration to concentrate sunlight up to____ times onto a fluid-filled tube positioned along the line of focus.
    100
  19. 3 similarities between electricity and magnetism.
    • -Both Create a force that can act in vacuum
    • -Can be either attracted or repulsed
    • -Both inversely proportional to the square of the distance between two charges or poles
  20. Ohms Law
    • V=IR
    • I=V/R
  21. Why do We transfer electricity at such High Voltages
    Because the higher the voltage the lower the current. Lower current lower power loss squared
  22. This is when the sun light strikes certain metals electrons are excited/emitted.?
    The Photoelectric Effect.
  23. In Hydro what types of turbines are good for high flow/ low head? What types are good for High Head/low flow?
    • Reaction Turbines
    • -High Flow/low head
    • Impulse
    • -High Head/low Flow
  24. Why isnt Tidal better explored? 2 reasons
    • Material Cost
    • Highly Corrosive.
  25. This motor takes in electrical energy and creates mechanical energy
    Electric Motor
  26. This motor takes in mechanical energy and produces electrical energy
    • Mechanical engine
    • -Generator
  27. This type of doping uses Boron and it creates space 4 electrons. It is missing electrons making it positive
    P-Type semiconductor
  28. This Semiconductor is doped in Phosphorus giving it extra electrons. this is known as ?
    N-type Semiconductor
  29. To increase voltage wire things in ?
    to increase voltage wire things in SERIES
  30. To increase Current Wire things?
    To increase Current wire in Parallel.
  31. The sun converts ______ tons of Hydrogen to helium every second
    650 million
  32. Radiation come in 2 different ways
    Wave/Particle. Briefly describe each.
    Wave- Frequency. Higher=more energy

    Particle- Photons=tine particles of energy
  33. Solar Energy can be split into  2 main purpuses
    • Direct electricity via PV
    • Heating
  34. Break down the word Photovoltaic to its roots
    Photo=?    Voltaic=?
    • Photo=Light
    • Voltaic=Electricity
  35. It goes Cell, ____, ______
    Cell, Module, Array
  36. What Causes Wind
    • Sun heats earth non uniformly-
    • Poles get less, Equator Gets More
    • Creates Convection Current
  37. Bernoullis Equation in basic terms
    In a moving fluid stream the higher the velocity the lower the pressure and vise-versa
  38. This is a mechanism that faces the wind turbine directly into the wind
    Yaw
  39. This mechanism turns the rotor out of the wind to protect it
    Furling
  40. Why 3 blades? Why not 1 or 2
    • Not 1-Mechanical integrity
    • Not 2- High pressure on blade up high, low pressure on lower blade, inbalanced and stressed.
  41. Rankin Cycle
    Working Fluid?
    Open/Closed?
    Typical Efficiency?
    Best Efficiency?
    TH?
    • Water/Steam
    • Closed
    • 30-35%
    • 44%
    • 1050degrees F
  42. Brayton Cycle (Gas Turbine Engine)
    Working Fluid?
    Open/Closed?
    Typical Efficiency?
    Best Efficiency?
    Th?
    • Air/Air + Combustion Products
    • Open
    • 33-35%
    • 40%
    • 2700Degress F
  43. Combined Rankin/Brayton Cycle
    Working Fluid?
    Open/closed
    Typical Efficiency?
    Best Efficiency?
    • Both Open/closed
    • 50-55%
    • 60%
  44. Wind energy is what type of blade and why?
    Reaction Blade because it acts on Bernoullis Equation
  45. 2 types of Concentration SOlar
    • Point Focus= Parabolic Dish/Power Tower x1000
    • Line Focus= Parabolic Troughx50
  46. stirling engine has ___ pistons called the ____ piston and the _____ pistons
    • 2 pistons
    • Power Piston
    • Displacement Piston
  47. 3interactions between electricity and Magnetism
    • -An electricla current produces a magnetic field
    • -A moving charged particle can experience a force in a magnetic field
    • -A wire moved in a magnetic field has a podtential difference across its ends

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