Thevenin vs Norton Theorem
Thevenin’s theorem and Norton’s theorem are two important theorems used in fields such as electrical engineering, electronic engineering, physics, circuit analysis and circuit modeling. These two theorems are used to reduce large circuits to simple voltage sources, current sources and resistors. These theories are very useful in calculating and simulating changes for large scale circuits. In this article, we are going to discuss the applications of Thevenin’s theorem and Norton’s theorem, their history, definitions, similarity between these two theorems and finally the differences between them.
A theorem is something that is defined on previously accepted theorems and axioms. If a result deviates from the theorem, it can be because of the theorem itself, or the theorems and axioms that were used to build the theorem were wrong. Thevenin’s theorem for linear electrical systems states that any number of voltage sources, current sources and resistors can be reduced to an equivalent voltage source and a resistor connected in series with the voltage source. Even though it is known as Thevenin’s theorem, it was first discovered by Hermann von Helmholtz, a German scientist. It was first discovered in 1853. Later, the French telegraph engineer Leon Charles Thevenin rediscovered it in 1883. This is a very useful theorem in circuit theory. It can also be used for alternate current circuits by using impedance instead of resistance. The Thevenin’s equivalent circuit is usually calculated for an open circuit. Then the result is used to model and simulate how the circuit will behave when different components are used to close the circuit path. This theorem is very useful because of the conversion of real life components to ideal components. The properties of these ideal components are relatively easy to calculate.
The Norton’s theorem is also for linear networks. The Norton’s theorem states that any number of voltage sources, current sources and resistors having two open ends can be simplified into an ideal current source and a resistor connected in parallel with the source. This theorem can also be used to alternative current circuits by applying impedance instead of resistance. The Norton’s theorem was discovered separately by two people. They were Hans Ferdinand Mayer and Edward Lawry Norton. Therefore, the Norton’s theorem is also referred as Norton-Mayer theorem in some parts of Europe. This theorem is also very useful when it comes to circuit simulations. The Norton’s resistance is also equal to the Thevenin’s resistance. The Norton’s law was discovered much later than the Thevenin’s law in 1926.
What is the difference between Thevenin and Norton theorems?
- Norton’s theorem uses a current source, whereas Thevenin’s theorem uses a voltage source.
- Thevenin’s theorem uses a resistor in series, while Norton’s theorem uses a resister set in parallel with the source.
- Norton’s theorem is actually a derivation of the Thevenin’s theorem.
- The Norton’s resistance and Thevenin’s resistance are equal in magnitude.
- The Norton’s equivalent circuit and Thevenin’s equivalent circuit can be easily interchanged.