How to use the Norton Equivalent Calculator
- 1. Pick the networkDivider, two sources, bridge, current source, measured values or a Thevenin model.
- 2. Type the valuesUse plain numbers or prefixes like 4.7k and 2m.
- 3. Read IN and RNEach step is shown, with a check against Vth.
How the Norton equivalent is found
The Norton equivalent replaces a network with a current source IN in parallel with a resistor RN. IN is the current that flows through a wire placed across terminals a-b. RN is found exactly like Rth: short independent voltage sources, open current sources and look in from a-b. Source transformation links the two models: IN = Vth/Rth and RN = Rth.
Worked example: Vs = 12 V, R1 = 4 kΩ, R2 = 6 kΩ, R3 = 1.6 kΩ. Short a-b, so R3 is in parallel with R2: 6 ∥ 1.6 = 1.263 kΩ. The source current is 12/(4 + 1.263) = 2.28 mA, and the current divider sends 2.28 × 6/7.6 = 1.8 mA through the short. RN = 1.6 + 4 ∥ 6 = 4 kΩ, and IN × RN = 7.2 V, which equals Vth.
Exam tips for Norton questions
- Draw the short across a-b before you write any equation. It often puts resistors in parallel.
- Use the current divider rule: I through a branch = I total × (other resistance)/(sum).
- A load RL takes IL = IN × RN/(RN + RL).
- If you already know Vth and Rth, the conversion takes one line. Examiners often ask for both models.
The tool finds IN directly with the short in place and then checks it against Vth/Rth.
Frequently asked questions
Is the Norton resistance the same as the Thevenin resistance?
Yes. RN = Rth for the same pair of terminals. Only the source model changes, from a voltage source in series to a current source in parallel.
How do I convert Thevenin to Norton?
Choose 'Convert a Thevenin equivalent'. IN = Vth/Rth and RN = Rth.
What does a negative IN mean?
The short-circuit current flows from b to a instead of from a to b. Flip the arrow of the current source.
Is this tool free?
Yes. You fill in a short form once to see your result, and the other Uncodemy tools then open without it. All the maths runs in your browser.