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How is current same on both sides of a resistor

  1. May 24, 2014 #1
    How come that the current is equal on both the sides.The resistor should decrease the rate of flow of electrons i.e. current.
  2. jcsd
  3. May 24, 2014 #2
    If they weren't the same then you would have a build up of charge inside the resistor.

    It's like when water goes in one end of a hose it has to come out the other end.

    The resistor reduces the potential of the current. It would be the same as having some restriction inside the water hose. The same water that goes in would come out but it would lose some pressure. The restriction would also slow down the flow of water.

    The resistor does decrease the rate of flow. What goes in still has to come out so the current is the same on both ends.
  4. May 24, 2014 #3
    But I think that the resistor does resist the flow of electrons through it and that is why it gets heated up.
  5. May 25, 2014 #4


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    The usual analogy is water flowing thru a pipe: every drop of water entering a section also leaves that section, even if the size of the pipe changes ... which results in a pressur change. Pressure is analogous to voltage, while water flow is analogous to pressure.

    The presence of resistance is thus like a change in pressure.

    The analogy isn't perfect, but "what goes in must come out" is valid in both.
  6. May 25, 2014 #5


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    That is correct and has nothing to do with the fact that what goes in must come out. The resistor inhibits the AMOUNT of flow through it (larger resistors, in ohms, allow less current) but it is still true that however much goes in must come out.
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