Engineering 44 pesquivel: (4/13/17) Day 15: Capacitor and Inductor Voltage-Current Relations

Day 15

Lecture

In lecture we went over the basics of analyzing capacitor circuits, including how to add up equivalent capacitances and how they behave under constant conditions.

Lab 1

Capacitor Voltage-Current Relations

In this lab, my team and I observed the behavior of a capacitor under AC conditions. This taught us to further use the oscilloscope function on the analog discovery units while gaining more insight on a capacitors place in our calculations.

Prelab:

For the prelab, we made graphs of the current through the capacitor over time against the voltage on it over time.

During the fabrication process we made a simple circuit utilizing a capacitor of 1 microFarad and resistor of 100 ohms, along with the oscilloscope and wave generator from our analog discovery.

We ran a few different frequency waves to observe the capacitor voltage (Blue), current (Red), and input voltage (Yellow).

This is a sinusoidal wave input at 1kHz

iC = 10mA

This is a 100Hz Triangular Wave input.

iC = 1.5mA

Lastly, we tried a 2kHz sinusoidal input.

iC = 20mA

From these results, we can mostly gather that our initial sketches were way off. The behavior of a capacitor under these conditions can best be predicted using

Lab 2

Inductor Voltage-Current Relations

This lab is mostly the same in terms of procedure and purpose. We want to see the behavior of current through an inductor as a function of the input voltage. To visually analyze this we will be using the same tools and graph format.

Prelab:

We were told to conceptualize the graph of a Cosine wave input being sent through an inductor and predict what the current would be.

With a mental image, we sought out to test our hypothesis through a simple circuit. The set up of the analog discovery device was mostly the same as the capacitor lab.

This time however, we only tested 2 frequencies on the inductor. The charts were the same as well, the inductor voltage (Blue), current (Red), and input voltage (Yellow).

First, a 1kHz sinusoidal wave with a 2V amplitude.