DC Circuits

IntroductionThis experiment is to analyse the basic concepts of DC circuits using thevenins theorem and Kirchoffss Law. Thevenins Theorem Maximum Power Transfer Mesh Analysis Nodal AnalysisThevenins TheoremAny combination of batteries and resistances with two terminals can be replaced by a single voltage source Eth and a single series resistor Rth. The value of Eth is the open circuit voltage at the terminals, and the value of Rth the resistance seen at terminals AB with the voltage sources replaced by short circuit and current sources replaced by open circuit.Maximum Power TransferMaximum power transfer theorem states that to obtain maximum external power from a source with a finite internal resistance, the resistance of the load must be equal to the resistance of the source.Mesh AnalysisThis is a method to measure the current or the voltages.Nodal AnalysisThis is a method to measure the voltages in the nodes of the circuit.

The calculated and the measured values were tabulated under results and observations. For thevenins theorem the power was calculated for load resistor using experimental and theoretical values and graph was plotted for load power and normalized resistance by using the values.

LOAD RESISTANCEMEASURED ORIGINAL NETWORKMEASURED THEVENINS EQUIVALENTCALCULATED THEORY

R(L)[ohms]V(RL)I(RL)V(RL)I(RL)Power(mW)V(RL)I(RL)Power(mW)

100.9V84.7mA0.90V87.5mA78.750.81V87.12mA75.79

473.25V68.7mA3.38V68.9mA232.883.23V68.92mA222.62

814.93V67.01mA4.87V57.18mA278.464.71V57.55mA271.10

1005.50V57.14mA5.38V53.15mA285.945.29V53.05mA280.64

1306.18V46.89mA5.81V48.10mA279.466.09V46.93mA285.83

1807.13V39.64mA7.16V39.37mA281.887.08V39.36mA278.72

2207.64V38.34mA7.71V35.67mA275.017.66V34.87mA267.11

3308.84V26.66mA8.83V26.77mA236.378.75V26.53mA232.17

4709.65V20.68mA9.61V20.56mA197.589.56V20.34mA194.49

100010.44V10.81mA9.99V10.70mA106.8910.79V10.80mA116.57

Results and ObservationThevenins Equivalent CircuitCalculated:Measured:

Load Power (W) Normalized power (RL/Rth)

0.078750.07

0.231880.36

0.278460.63

0.285940.76

0.279460.99

0.281881.38

0.275011.69

0.236372.53

0.197523.61

0.106897.68

Load Power (W)Normalized power (RL/Rth)

0.075790.07

0.222620.36

0.271100.63

0.280640.76

0.285830.99

0.278721.38

0.267111.69

0.232172.53

0.194493.61

0.116577.68

Mesh AnalysisQUANTITYMEASUREDCALCULATED

E118.04V18.0V

E29.98V10.0V

VR13.04V3.0V

VR212.50V12.3V

VR33.41V3.3V

VR49.08V8.93V

VR5-0.89V-0.90V

VR62.53V2.5V

IR125.59mA25.0mA

IR215.08mA15.0mA

IR310.38mA10.0mA

IR419.16mA19.0mA

IR5-8.98mA-9.0mA

Nodal AnalysisQUANTITYMEASUREDCALCULATED

E118.08V18.0V

E29.48V10.0V

VR115.53V15.471V

VR212.51V12.477V

VR39.09V9.058V

VR49.98V10.0V

VR5-2.54V-2.579V

IR125.59mA25.28mA

IR215.08mA15.16mA

IR310.38mA10.14mA

IR419.36mA19.33mA

IR5-3.48mA-19.28mA

IR625.11mA25.29mA

DiscussionThis lab session is about how to apply thevenins theorem to solve complicated circuits, and to solve loop circuits using nodal and mesh analysis. The circuits were made using breadboards, and power was supplied using power supplies and the values of the voltage and current were measured using Digital Multi meters (DMM).The measurement across resistors with lower resistance were taken faster to avoid over heating of the resistors. After the measurements were taken, the values were calculated using the theorems mentioned above, and graphs were plotted (are attached with this report). When the theoretical and the experimental values were compared there are difference in them, these may have mainly occurred due to the following The meters were considered to be ideal (practically they are not). Continuous usage Improper connection between resistors and breadboard Tolerance of multimeter

References www.wikipedia.com http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html

Sarujan k. [EN14084928]