1 Reply Latest reply on Oct 15, 2020 1:11 AM by michaelkellett

    Resistors in parallel

    salesm21

      I know this seems simple, it probably is. But I keep getting told that the first two resistors in this circuit (namely the 10k and 15k resistors) are in parallel and I just don't see it. The def of a parallel resistor is one that is attached across another resistors in a way that the both have the same voltage drop. The 10k is going to get a different voltage than the 15k because the 10k is in series with the source. Any help would be great.

        • Re: Resistors in parallel
          michaelkellett

          It's because a voltage source has an impedance or resistance of zero. So for impedance analysis you can set it to zero.

          Thevenin's theorem also states that you can replace a voltage source in series with a resistor with a current source in parallel with that resistance (or vice versa) - and everything works the same.

           

          There is a Wiki article (and lots of other stuff on the web Google Thevenin Theorem and Norton Theorem and Kirchoff for the full set of key linear circuit theorems).

           

          https://en.wikipedia.org/wiki/Th%C3%A9venin%27s_theorem

           

          But you are correct - the resitors are NOT in parallel, it is that the combination of voltage source and resistors can replaced by a single resistor (value = the two in parallel) and a voltage source (which will have a different voltage from the original source).

           

          I can't draw diagrams from here but there are lots on the web.

           

          MK