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Smiple circuit with just one resistor

  1. Mar 2, 2004 #1
    In a smiple circuit with just one resistor, consider the current that flows. If you increase the resistance, less current flows. If you increase the supply voltage, the current increases.
    One book says that increasing voltage provides charge with the energy needed to get through the resistor, but even when the supply voltage is very low, some charge still gets through doesnt it, just not very much.
    So increasing the voltage does increase the energy per coulomb, but this cant be the reason why more current flows can it, because the charge can get through even when it has a low energy?
    The only think i could think of is that a higher voltage makes the charge circulate faster due to the higher potential difference, but that sounds a bit wrong.
    Can anyone help me out please? Basically i just want to know how come increasing voltage increases the current? And how come when you increase the voltage, more energy is dissipated for a given resistance? Because it cant suddenly become harder for charge to get through a resistor when you inrease the supply voltage can it?
     
    Last edited: Mar 2, 2004
  2. jcsd
  3. Mar 2, 2004 #2

    krab

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    Science Advisor

    Think of a garden hose. Blow into it with your mouth. The pressure with which you blow is analogous to voltage. More pressure->more flow and also more energy dissipated.
    This implies you need a minimum energy to get through the resistor. That's wrong. A resistor is not a threshold device. Either the book is wrong or you paraphrased it incorrectly.
    That's absolutely right. It's the definition of voltage.
     
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