Day 8 - Thevenin's Theorem

Topics Discussed

On day 8 of the ENGR 44 course, we were introduced to the Thevenin's Theorem, which essentially is a theorem/application that allows us break down a rather large circuit into a simple single voltage source and single resistor, of which we call Thevenin voltage and Thevenin resistance respectively. After being introduced to the theorem, we applied it to numerous practice problems in class. (Fig. 1)

Fig. 1

We also touched base on some calculations involving finding the maximum power that could be delivered to some element attached to the Thevenin circuit diagram (Fig. 2)

Fig. 2

Thevenin's Theorem Lab

In the Thevenin's Theorem Lab, we sought to verify Thevenin's Theorem and see whether our not the Thevenin Resistance and Voltage would yield results similar to those calculated. To begin, we drew a diagram of the circuit and proceeded to find the Thevenin resistance and voltage. (Fig. 3) 

Fig. 3

Once we had our values calculated, we proceed to create the circuit without the voltage sources. We would then measure the resistance of the entire circuit to verify whether or not the Thevenin resistance was true. We then input the voltage sources and attached a potentiometer to the circuit. (Fig. 4) We compared our measured values to our calculated values. (Fig. 5)

Fig. 4

Fig.5

We then proceeded to vary the resistance within the potentiometer to create a graph with the said data points reflecting the power vs resistance and yielded a decent graph that illustrated an upward slope. (Fig. 6)

Fig. 6

Summary

In this lab, we were able to verify Thevenin's Theorom and ultimately see how it could be put into practical use. By finding the Thevenin resistance and voltage, we could essentially find the maximum power that could be dissipated across some device, which in our case was a potentiometer.