Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

I was talking about the meeting of the first class of my Introduction to Electricity and Magnetism laboratory students for the eleventh week of the first term.

There was a problem with the first part of the experiment when the students were trying to get the galvanometer pointer of full deflection.

Since we weren't using decade resistor boxes like the procedure required, we had variable knob resistors instead, that could not be given specific numeric values, only slight turns of the knob that had to be measured afterwards.

First off, they weren't getting any readings whatsoever on their meters, which could only be attributed to the alligator clip connectors they soldered being loose – and in need of repair on their side.

Another remedy is to the dilemma is not to follow the manual in starting with a resistor of 99,999 ohms, but something with a lesser value that is easy to adjust, such as 500 ohms or even smaller.

Next up, they couldn't read the value of the resistor when they had already fixed the pointer to full deflection and then the next resistor to half deflection.

I finally had to allow them to use a digital multimeter only to find that the value is less than one ohm. From there, computing the needed shunt resistance to use was also a very small resistance that could only be obtained by placing several integer valued resistors in parallel.

We had to determine those parallel resistances from the reciprocals of one digit resistors and ten (the smallest resistor we had, and the smallest potentiometer as well). Now I'm tempted to have this as part of their lecture exam.

I also had to give the class different values for their constructed ammeters and voltmeters per group so as not to have the same computations.

One more thing: we could only use two variable power supplies as the other class was using the rest, so we only had two set-ups.

Session 1241 made shoddy connectors. Class dismissed.