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    (Original post by madredjake)
    Q: Explain the role of step up and step down transformers
    Step up transformers increase the voltage and decrease the current for the same power to increase efficentcy as there is less wasted heat energy produced. Step down transformers, step down the volatge for use in home.
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    (Original post by Mahrez)
    Explain how convection occurs in an immersion heater?
    1. at the bottom water is heated by conduction
    2. this gives water more kinetic energy and so more movement
    2. this makes them move away from each other more creating large gaps between particles.
    3. creates expansion
    4. the warm water becomes less dense and rises
    5. it rises above the cool dense water and displaces it
    6. the cool water falls and fills in the gap created by the warm water rising
    7. the cool water is heated again
    8. this is called convection currents, a circulation of the fluid water.

    thank you hafsa!!
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    (Original post by madredjake)
    Q: Explain the role of step up and step down transformers
    Step up transformers increase the voltage within the National Grid to 132,000V so less energy is lost along the cables.
    The voltage is then stepped down by the step down transformers to 230V to make it safe for houses.

    What is a U-Value?
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    (Original post by TeenPolyglot)
    Step up transformers increase the voltage within the National Grid to 132,000V so less energy is lost along the cables.
    The voltage is then stepped down by the step down transformers to 230V to make it safe for houses.

    What is a U-Value?
    U-value is how effective a material is.

    Explain condensation and evaporation
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    (Original post by madredjake)
    Q: Explain the role of step up and step down transformers
    Step up transformers increase the voltage up to 400,000 volts and reduces the current to a low level so that minimul heat loss occurs throughout the cables and pylons to increase efficieny as energy transfer would be kept low.
    Step dwn transformers reduce the voltage down to 230V so that it can be used suitably for consumer appliances and also because it's so much safer.

    BOOM
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    (Original post by madredjake)
    Q: Explain the role of step up and step down transformers
    step up increase voltage and decrease current, and step down decrease voltage and increase current, so that the least amount of energy is wasted and lost to the surroundings as heat.
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    What is a U-Value?[/QUOTE]

    U-value is the measure of how effective a material is as an insulator.
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    (Original post by CaSama9)
    1. at the bottom water is heated by conduction
    2. this gives water more kinetic energy and so more movement
    2. this makes them move away from each other more creating large gaps between particles.
    3. creates expansion
    4. the warm water becomes less dense and rises
    5. it rises above the cool dense water and displaces it
    6. the cool water falls and fills in the gap created by the warm water rising
    7. the cool water is heated again
    8. this is called convection, a circulation of the fluid water.
    its called convection CURRENTS :P
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    (Original post by nisha.sri)
    U-value is how effective a material is.

    Explain condensation and evaporation
    Condensation is when a gas rich in Kinetic energy which has overcome attractive forces, loses energy and has particles which slowed down, and form forces again attracting particles closer together forming a liquid.

    Evaporation is when energetic particles escape the surface of a liquid.

    Explain how the surface of a mirror becomes misty in a shower.
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    (Original post by nisha.sri)
    U-value is how effective a material is.

    Explain condensation and evaporation
    Evapouration is when the particles gain kinetic energy, become less dense and expand and rise. The particles have weak forces of attraction hence it is gas.
    Condensation is when the gas cools at the surface, loosing it's kinetic energy.
    The rate of evapouration depends on:
    surface area
    area flow

    Rate of condensation depends on:
    Density
    Airflow
    Temperature
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    explain the cooling effect (3 marks)
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    (Original post by madredjake)
    What is a U-Value?
    U-value is the measure of how quick energy is transfered in a material and therefore how effective an insulating material is

    What factors affect the rate of Evaporation and condensation? loads of marks
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    (Original post by hafsa473)
    explain the cooling effect (3 marks)
    The particles woith higher kinetic energy will evapourate into the atmosphere thus decreasing the overall/mean kinetic energy in the container
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    (Original post by Mahrez)
    Evapouration is when the particles gain kinetic energy, become less dense and expand and rise. The particles have weak forces of attraction hence it is gas.
    Condensation is when the gas cools at the surface, loosing it's kinetic energy.
    The rate of evapouration depends on:
    surface area
    area flow

    Rate of condensation depends on:
    Density
    Airflow
    Temperature
    Perfect but I think you're mixing this with convection, it's better to just say that energetic particles escape
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    (Original post by CaSama9)
    U-value is the measure of how quick energy is transfered in a material and therefore how effective an insulating material is

    What factors affect the rate of Evaporation and condensation? loads of marks
    Evaporation - S.A,Temperature,Air flowing, Density
    Condensation - S.A, Density,Air flowing

    Why does a mirror get misty ?
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    (Original post by CaSama9)
    Perfect but I think you're mixing this with convection, it's better to just say that energetic particles escape
    but technically thats how particles escape but I might be tbh
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    (Original post by Mahrez)
    The particles woith higher kinetic energy will evapourate into the atmosphere thus decreasing the overall/mean kinetic energy in the container
    tut tut wheres the 3rd mark
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    Explain how a hydroelectric plant is used to generate electricity
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    (Original post by hafsa473)
    tut tut wheres the 3rd mark
    particles gain kinetic energy become less dense rise and escape etc
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    (Original post by CaSama9)
    U-value is the measure of how quick energy is transfered in a material and therefore how effective an insulating material is

    What factors affect the rate of Evaporation and condensation? loads of marks
    Evaporation:
    Low Density
    Temperature of liquid is higher
    Airflow is greater
    Larger surface area

    Condensation:
    Temperature is lower
    Temperature of the surface which the gas touches is lower
    Concentration is higher

    Why do you hear a delay between the sound produced and the reflected sound?
 
 
 
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