I am well aware of the importance (more appropriately, implication) of Thevenin's theorem in real-life circuits. Output impedance of amplifiers and the 'stiffness' of a power supply (such as the domestic mains power) has its theoretical roots in the Thevenin's theorem. See Norton's and Thevenin's theorems importance.

What I am not able to get is the need or importance of the Norton's theorem in a similar way, beyond undergraduate education. Are there any practical uses or importance of the Norton's theorem in any domain of electrical engineering (or even beyond!)?

  • \$\begingroup\$ Like what's the Newton's theorem importance in real physics, or Pitagora in mathematics. \$\endgroup\$ Apr 1, 2017 at 17:28
  • \$\begingroup\$ From the answer of the question you linked: "For the same reasons its dual twin, Norton's theorem, is used (a bit less commonly)." \$\endgroup\$
    – uint128_t
    Apr 1, 2017 at 18:08
  • \$\begingroup\$ Norton's is dual to Thevenin's. \$\endgroup\$
    – jonk
    Apr 1, 2017 at 18:08

1 Answer 1


Both theorums side by side (courtesy of hyperphysics): -

enter image description here

Basically, Norton converts a bunch of resistors attached to a voltage source into a current source in parallel with a single equivalent resistor and Thevenin does the same except it converts to a voltage source in series with a single equivalent resistor.

The last time I used this was yesterday and I used both and I regularly use both.

Are there any practical uses or importance of the Norton's theorem in any domain of electrical engineering

Yes there are. I had a voltage source feeding a parallel capacitor via a resistor. I converted the V and R to a current source. Now I have a current source with parallel R and C. I then converted back to a voltage source so it became R||C in series with the new voltage source and it made the problem mathematically easier for me.

In other words I broke down the problem into simpler jumps; I could have just done the whole math but there were other complications because following the R||C was another series capacitor and inductor to ground. (Basically it was solving the resonant frequency for a Colpitts common collector BJT oscillator and analysing the loop gain at resonance.

So I used Nortons, followed by Thevenins. I'd say I use neither quite often but when I do use one of them it's likely to be in equal amounts to the other one.

I'm aware that this answer is an opinion but I felt that giving an example was useful.

  • \$\begingroup\$ So its mostly for circuit analysis of real circuits then if I am not mistaken? Anyway the example was quite good \$\endgroup\$ Apr 2, 2017 at 13:39
  • 1
    \$\begingroup\$ Yes it is and it breaks the problem down to simpler chunks. Sometimes, the simpler chunks lead to better intuition on the problem rather than just developing one big formula. \$\endgroup\$
    – Andy aka
    Apr 2, 2017 at 14:57

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