Gas station without pumps

2014 April 25

Ag/AgCl electrode lab went fairly well

Filed under: Circuits course — gasstationwithoutpumps @ 00:08
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Today’s electrode lab also went fairly well.  Most of the students finished on time (or nearly), though  I stayed an hour late with the singleton student—this is a lab that goes much faster if one student records data while the other reads the meters, so I again served as meter-reader for him after everyone else had left.

I still have to get the students to start lab more efficiently. Students took a long time before they had their electroplating setups ready to go, though there was almost nothing to do if they had made their schematics ahead of time.  We again had problems with a couple of the students getting no current (for the electroplating), because someone in another lab had blown out the fuses on the ammeters.  That I was able to debug for them, but it added an extra half hour to their lab time as they tried to debug their circuits first without my help. I still had a couple of groups trying to put ammeters across the electrodes, instead of in series with them, but because they have had drilled into them to limit the current before turning on the output to the power supplies, I don’t believe that they blew any fuses.

The group that was working the fastest today—at least 40 minutes ahead of every other group—was embarassed when I noticed that they had connected up the probes wrong on one of the multimeters, so that the voltage measurements they had been taking on that meter were just noise from floating wires. This group was the one I expected the best work from, but by not checking their wiring carefully, they went from being the fastest group to the slowest one.  I think they did make up the time and still finish on time, redoing all the measurements.

The 1 liter of each salt solution was barely enough for 5 groups for the stainless steel and Ag/AgCl electrodes.  I think that next year I’ll want 150ml per student, to be sure of having enough. I’ll probably also switch to 1M, 0.1M, 0.001M, and tap water, reducing the measurements from 5 sets to 4 sets. I wish that there were an easy way to automate the measurements, as the frequency adjustment and data reading is fairly tedious.

I spent most of this evening catching up on my e-mail and writing the quiz for tomorrow’s class.I’ll have to get in somewhat early tomorrow, to get copies of the exam printed before class.

I won’t have much free time tomorrow, as I have my weekly office hours, and tomorrow is the deadline for students declaring majors. I’ve had a steady stream of students in my office for the past couple of weeks, but I suspect that there will be a lot of people who just figure that they can drop in at the last moment.  They’ll be out of luck, because I have 4 students scheduled for half hour slots, filling my 2 office hours.





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