superposition theorem on an unbalanced bridge

Discussion in 'Homework Help' started by davebee, May 29, 2009.

  1. davebee

    Thread Starter Well-Known Member

    Oct 22, 2008
    Last night my daughter came to me for help with a circuit problem that her high school physics teacher had handed out which was identical to figure three of the page at this link except that her voltage and resistors had different values.

    where the assignment was to derive the voltages and currents across each resistor.

    Hallikainen said that superposition can be used to solve this by redrawing the circuit as in his figure 4.

    Searching for how to do superposition led us to this link, which described how to do superposition analysis very nicely:

    My question is that near the end of the page, the allaboutcircuits page says that superposition cannot be used to analyze an unbalanced bridge circuit.

    But isn't that what Hallikainen just did? Who's right?
  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    Yes he did and he's correct.
  3. AdrianN

    Active Member

    Apr 27, 2009
    Indeed, Hallikainen is correct.

    Another way to solve the loaded unbalanced bridge is to use the delta to star resistor network transformation for the delta formed by R2, R4 and R5, and then use simple attenuator equations.