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What's the electrical power (physically)

  1. Oct 9, 2012 #1
    I have a question to depth understanding electricity

    what's the thing that make electrical power appear???

    I mean that when generating electrical power
    We generate emf (voltage)
    and if the circuit was closed we get current !!

  2. jcsd
  3. Oct 9, 2012 #2


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    Staff: Mentor

    Same charges repel each other, opposite charges attract each other. If you have different charge densities in different places, charges "try" to reach the other side (but need some conducting connection to do so).
    This is a very simple (and slightly inaccurate) description how you can get current flows.

    Look in a text book for a proper introduction.
  4. Oct 9, 2012 #3
    I'm asking about what make "POWER" generated?? and how???
    I know
    we generate current and voltage and power = VI

    I'm asking what's the power reason for appear
  5. Oct 9, 2012 #4


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    Voltage is roughly analogous to elevation. Electrons will "fall" toward the higher positive voltage, converting potential energy to kinetic energy. This kinetic energy can be harnessed to light up a light bulb or something. When these electrons move through a wire, they collide with each other and the wire and cause the wire to heat up.
  6. Oct 9, 2012 #5


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    One way is this: work of some sort is done --- water falling over a dam for example --- and is converted into electrical energy, which is sent over wires, and then causes motion in electrical motors which can do work (expending power).
  7. Oct 9, 2012 #6
    klm: that's a good question...not so easy to answer without some understanding of basic physics...like electric potential....Check Wikipedia if you'd like more on that.

    In SOURCES of electric power, charges are forced to move by an external emf from a lower to a higher potential and power [really energy] therefore resides in the individual charges. This can be accomplished via mechanical or chemcial means [generators or batteries respectively].

    In LOADS, like light bulbs or electric motors in a refrigerator, the charges move from the higher potential to a lower potential and some of the original energy is recovered.....some has already been lost via transmission losses.

    Energy in electronic elements

    Some elements in a circuit can convert energy from one form to another. For example, a resistor converts electrical energy to heat, this is known as the Joule effect. A capacitor stores it in its electric field. The total electric potential energy stored in a capacitor is given by 1/2C V2where C is the capacitance, V is the electric potential difference...

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