Day 18 - Sinusoids and Phasors

Topics Discussed

On day 18 of the ENGR 44 course, we were introduced to the topics of sinusoids and phasors. Sinusoids are signals that vary according to an alternating sine or cosine function. We did several practice problems with these concepts. (Fig. 1) We also discussed using phasors which are phase shifts within these sinusoids. We practiced several methods used to add, subtract, multiply, and divide these phasors, including how to convert them from polar to rectangular coordinates and vice-versa.

Fig. 1

Passive RL Circuit Response Lab

In lab we planned to make an RL circuit and analyze the effects on said circuit when applying a sinusoidal voltage function. Using the phase shift within our calculations, we were able to find theoretical amplitude gains that were given by a formula within the lab manual. (Fig. 2)

Fig. 2

Once we had our theoretical values, we then proceeded to create the circuit and analyzed the phase shift and gains and found that we were relatively close to our theoretical values. (Fig. 3)

Fig. 3

Summary

Upon completion of the lab, we were able to successfully analyze an RL circuit that had an alternating voltage applied to it. We were able to find the gain and phase shift across the inductor and resistor. Since AC circuits are the most common circuits we find based off of the alternating nature of circuits in our day-to-day lives, being able to properly investigate the effects on certain elements in the circuit becomes extremely useful.