ASU Spring 2017 Session B Week 5 Update

It’s been a busy and tough week school wise, but I’m ahead enough that I’m hoping to enjoy the Easter holiday with family and not have to worry about school.

In PHY 241 this week I took the second test on Tuesday. I did well and scored a 101/100. The professor had it 108/100, but I keyed in the wrong value in the calculator and didn’t catch it. Had it down on paper correct. I hate it when that happens, but I’ll gladly take that score and hope to not make that kind of careless mistake again.

With Waves and Optics done, the class turns its attention to relativity and modern physics. Chapter 36 cover’s Einstein’s Principle of Relativity. All new info for me. I remember the famous E=mc² formula, but don’t remember ever really having to work with it. Hopefully over the next few days I’ll better understand it and the other topics discussed like time dilation, the Lorentz transformations and relativistic momentum, velocity and energy. It’s all very interesting stuff.

So far though, PHY 241 has been a much more straight forward set of lectures and homework than the other two classes here at ASU.

EEE 202 was really interesting this week. More crazy math, but once I figured out how to switch my calculator over to polar and work with it, the math was really pretty straight forward. This week the class had us looking at AC Steady State Analysis so thinks like sinusoids and phasors, phasors and complex numbers, impedance and admittance and frequency domain analysis.

The lectures for the class are still far too short but between the recitation sessions and the worked homework solutions I’ve been studying, slowly making my way through the material. Just wish I had more time to really practice and study. I’m having the worst time remembering the different formulas and need to put together another Anki deck. I should have done that sooner, but no use lingering on what I should have done.

This week’s Lab 5 was really neat. It look me a little bit to sort out, but we were studying first order RC and RL circuits. The lab asked us to put simulate them in LTspice, then use MATLAB to plot the response and then finally we built them, setup a custom wave form and then use the oscilloscope to view the waveform.

The waveform was a pretty standard pulse that was on for 100 microsecond then off for a total period of 200 microseconds. It had a 1 microsecond rise and fall though. It took a little bit of tinkering in MATLAB and I learned about the Heaviside capabilities MATLAB has to solve the problem. Once I had the equation for the current, it was pretty straightforward then to find the voltage through the resistor and the inductor or capacitor. It was a nice feeling to see the MATLAB plot match what I had in LTspice when it all came together.

At first I neglected to enter the rise and fall into the waveform and had some really odd oscilloscope readings. It took a little bit to figure out the custom wave form options in the Digilent software, but if anyone is interested, here is an Excel workbook, Graves Lab 5 Waveform, that could be saved as a CSV and then imported into the Digilent Waveform software to save some time. This cleared up the issue and the oscilloscope waveform match the simulation and MATLAB.

Here’s a shot of one of the pretty MATLAB plot:

lab5-RL

Good stuff!

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