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Potential and Resistance

  1. Sep 14, 2014 #1
    Does the potential decrease when it charges(electricity) pass through a resistance?
    Newbie here....plz help :)
     
  2. jcsd
  3. Sep 14, 2014 #2
    Generally, yes, but much depends on how the potential is created in the first place. You may want to describe the situation that you have in mind.
     
  4. Sep 14, 2014 #3
    No actually, current flows from higher potential to lower potential....so when the current reaches the resistance it is at a higher potential & whn it leaves, potential decreases.....
    Now in the book the dirn of current is considered oppo....that is from lower to higher potential....in this case potential increases after charges pass thru the resistance....
    ***
    Am I right?
     
  5. Sep 14, 2014 #4
    I misunderstood your question and did not, myself, use correct terminology.

    When charges are moved by a potential difference, the potential difference generally decreases in magnitude.

    The potentials in a potential difference can become lower or greater in this process.
     
  6. Sep 14, 2014 #5

    sophiecentaur

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    Energy will always end up somewhere and you don't get any from nowhere. The charges are dissipating energy as they go through a resistor (a resistor will get hot, if enough power is dissipated). That energy comes from the lost electrical potential as they move through the circuit. Charges that 'creep into' the negative terminal of the battery have none left (using the convention that the negative terminal is at Zero Potential.) The battery (generator) gives new charges, coming from the positive terminal, more potential.

    Be careful using water analogies but you could look at the situation in a chain of resistors as being like a series of water wheels, down a hill, fed with water at the top, with the full gravitational potential energy. Each water wheel takes its share of the gravitational potential energy and the water emerging from the bottom wheel flows very slowly out into the drain, having lost its potential energy in stages.
     
  7. Sep 14, 2014 #6

    But the potential is equal at equal heights whether the wheels are there or not, right?
     
  8. Sep 14, 2014 #7

    sophiecentaur

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    Potential energy would be mgh. Without the wheels to take the energy off, the falling water would go faster and faster ( kinetic energy) and the analogy falls down. The charges / resistors are like the water / wheels. Without the resistors - say you had electrons through a vacuum, they would acquire all the Potential Enery as Kinetic. A different situation but, if course, Potential would still drop on the way.
    Electrical Energy is QV.
     
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