# Thevenin’s Theorem

Thevenin’s Theorem is simply a method used in simplifying a complex circuits or networks,easier and faster. In 1893, a French Engineer called M.L Thevenin , made this theorem.

*Thevenin’s Theorem* may be stated as “It is possible to simplify any complex circuit/linear circuit with Current and Voltage sources with an equivalent circuit containing a single Voltage Source connected in series to a load.

## Simple Steps To Solve Electric Circuit By Thevenin’s Theorem

1. Open the load resistor.

2. Calculate the Open Circuit Voltage. This is the Thevenin Voltage (V TH).

3. Short Voltage Sources and calculate the Open Circuit Resistance. This is the Thevenin Resistance (R TH ).

4. Now, Redraw the circuit with the calculated open circuit Voltage (V TH ) in Step (2) as voltage Source and the calculated open circuit resistance (R TH ) in step (3) connected in series to the load resistor that was removed in step (1). This is the Equivalent Thevenin Circuit of that Linear Electric Network or Complex circuit which had to be simplified and solved by Thevenin’s Theorem you have done.

5. Finally, find the Total current flowing through Load resistor by using the Ohm’s Law

**Example:**

**Solution**

**Step 1**

Open the load circuit

**Step 2**

Calculate the open voltage which will be the thevenin theorem.

For the 10Ω resistor,since it is an open-circuit,thus no current flows through it. The voltage across it is zero. The thevenin voltage will the voltage in R50 because it is connected in parallel with R10.

Since the 20Ω and 50Ω resistors are connected in series,the same current flows through each of the resistors.

Using Voltage Divider Rule to get voltage in R50

;

**Step 3**

Short the Voltage Sources and calculate the Open Circuit Resistance. This is the Thevenin Resistance (R TH ). We start the calculation from the direction of the arrow.

It is very clear that the 10Ω resistor is in series with a parallel connection of 20Ω and 50Ω resistor. I.e 10Ω+ (20Ω ll 50Ω)…(ll means parallel with)

;

**Step 4**

Connect the VTH and RTH in series with the removed load resistor.

**Step 5**

Using to find the current in the load resistor.

;

Load voltage; from Ohm’s law

;

Very easy isn’t it?

## Leave a Reply