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Theories and Laws ==>

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What Is Phase

RMS And Peak To Peak

Pulses

Pulse Modulation

Magnetism

Heat

Harmonics

Generator Principle

Filters

Electro Magnetism

Conductors And Insulators

Clippers And Limiters

Norton's Theorem

Thévenin's Theorem

Superposition Theorem

Frequency Modulation

The Right-hand Rule

Coulomb's Law

Gauss's Law

Ampere's Law

OHM's Law

Kirchoff's Current Law

Kirchhoff's Voltage Laws

23 topics total

RMS And Peak To Peak

Pulses

Pulse Modulation

Magnetism

Heat

Harmonics

Generator Principle

Filters

Electro Magnetism

Conductors And Insulators

Clippers And Limiters

Norton's Theorem

Thévenin's Theorem

Superposition Theorem

Frequency Modulation

The Right-hand Rule

Coulomb's Law

Gauss's Law

Ampere's Law

OHM's Law

Kirchoff's Current Law

Kirchhoff's Voltage Laws

23 topics total

Thévenin's Theorem

**Procedure**:

Connect the circuit as it shown in Figure 4.
**Table 1**

Two universal instruments

Keywords : Thévenin's, Theorem, Superposition, Formula, Electronic, Electric, Electrical, Voltage, Analysis
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**Writer : delon** |

In this lab project we examine series-parallel circuit in order to determine the current in one specific branch of the examined circuit (usually load current). DC Power Supply supplies the circuit with time-constant electromotive force. Analyzes will be provided by Thevenin's Theorem. The purpose of the project is to verify the theory of Thevenin's Theorem.

**Theory Part 1**

**Thevenin's Theorem**

Thevenin's Theorem can be demonstrated using the circuit shown in Figure 1. In Figure 1 is shown circuit with four resistors

and *R*_{L},

connected with voltage generator with electromotive force *E*=20 V. The assignment is to determine current *I*_{L }trough resistor *R*_{L}.

The calculation of the expected current trough and the voltage across the resistor*R _{L }*can be simplified by using Thevenin's Theorem. If the entire circuit with the exception of terminals A and B were enclosed in a

If these Thevenin equivalent values are known, the expected current through, and the

voltage across*R*_{L }may be calculated easily by using Ohm's Law. The Thevenin voltage,

*E*_{T}, appears the unloaded terminals A and B. Since no current flow through*R*_{3} in Figure 2

when A and B are unloaded, the voltage appearing across terminals A and B is the same

as the voltage appearing across*R*_{2}. Therefore *E*_{T}=*E*_{R2}. Assume a 20 V dc input and

calculate the Thevenin voltage*E*_{T }across terminals A and B.

voltage across

when A and B are unloaded, the voltage appearing across terminals A and B is the same

as the voltage appearing across

calculate the Thevenin voltage

Now, calculate the Thevenin equivalent resistance RT, appearing across terminals A and

B. Assume that a direct short replaces the 20 V dc power source. Therefore, *R _{1}*, is now in

parallel with

resistance

In Figure 3 are shown two identical circuit (The circuit from Figure 1 and the equivalent

Thevenin circuit)

Thevenin circuit)

Calculate the current *I _{L}* through resistance

**Practice Part 1**

**Equipment**:

- Breadboard
- DC Power Supply with time-constant EMF (0 to 25.0V DC)
- Three resistors with: and one variable resistor,
- Two universal instruments.

Connect the circuit as it shown in Figure 4.

**Experimental determination of equivalent Thevenin generator**

1) Disconnect the ammeter and variable resistance *R _{L}*. Set up the voltage on 20 V.

2) Connect the voltmeter between terminals A and B and measure the Thevenin voltage generator

3) Connect the ammeter and measure the current of short circuit between

terminals A and B with *(R _{L}=0) *

4) Calculate the equivalent resistance ( *R _{L}*=0 – short circuit on terminals A

and B).

**Experimental determination of the current I_{L }and the power P_{L} for the resistor R_{L}**

5) Connect again the circuit shown in Figure 4. Set up and keep the voltage at 20V. Changing the resistance of the variable resistor *R _{L }*for the values in Table 1 measure and record the values of current

Measured | Measured | Calculated | |

R_{l} (k?) |
I (mA)_{l} |
U_{l}=R_{l} I_{l} |
Power (W) P_{l}= U_{l} I_{l} |

0 | |||

2 | |||

4 | |||

_{6} |
|||

_{8} |
|||

R_{T} |
|||

? |

6) From the data in Table 1 draw graphs for the *U _{L}*

and one variable resistor

**Procedure**:

7) In Figure 5 is shown equivalent Thevenin circuit. Connect the component of the circuit and set the voltage of the source at the equivalent Thevenin voltage*E _{T}* calculated in Theory Part 1.

8) Connect one of the multimeters as a voltmeter across the source and the other as ammeter between the resistors R4=*R _{T }*and

9) Changing the resistance of the resistor *R _{L }*for the values in Table 2 measure and record the values of current

10) Calculate and record the power on the resistor *R _{L }*for the values from Table 2.

**Table 2**

Measured | Measured | Calculated | |

Resistance R_{l} (k?) |
Current I (mA)_{l} |
Voltage(V) U_{l}=R_{l} I_{l} |
Power (W) P_{l}= U_{l} I_{l} |

0 | |||

2 | |||

4 | |||

_{6} |
|||

_{8} |
|||

R_{T} |
|||

? |

11) From the data in Table 2 draw graph for the *U _{L}*=f (

12) What we can conclude from the results?

Keywords : Thévenin's, Theorem, Superposition, Formula, Electronic, Electric, Electrical, Voltage, Analysis

9 Mar 2006 Thr

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