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

It’s Wednesday morning and finally I’m talking about what happened at the start of the week. I’m exercising a little discretion (just a little) to be able to catch up with my relaying of what happened at work, without falling too much behind. But there’s just so much I want to tell.

Last Monday in my electricity and magnetism lecture class, since we are on the second to the last topic before the end of the term and there are still three weeks of classes left, I just gave them three practice problems on resistors in series and parallel and multi-loop multi-EMF circuits.

The first one only had five resistors in three series and parallel combinations where the values of the resistors are given as well as the potential difference from the only energy source.

From this they were supposed to get 22 different values. The first four were the equivalent resistor values of the different parallel and series sections of the circuit, given subscripted names depending on the node letters that they encompass. These they could (and did) solve one after the other.

After this they were supposed to get the current and voltage passing through the individual resistors, as well as in each set of nodes with equivalent resistance. There were nine values each, giving eighteen total.

Unlike the first part with the resistances though they could not have solved all of the currents first then all of the voltages. They would have to use the knowledge when current is equal through each component (in series) and when voltage is equal (in parallel) to find out which value they could solve first. Then they had to use Ohm’s Law to be able to get the value (either current or voltage), which was not equal but additively distributed.

They were still a little slow on this though, that they took approximately two thirds of the period just to finish this. Maybe I’ll give them more examples on this before the next exam.

This meant that when the period was over, they had not yet finished with the first Kirchhoff’s Rules application example with only three branches (but with three EMF sources), where they had to assign the direction of the three currents as well as the directions of the loops. And the fact that there were only two resistor values for the five resistors and two different values for the three EMF sources seem to have confused them more than it made the computation easier.

Only one of the fourteen students was able to finish this before the session ended.
He would only have to submit the third problem as an assignment, unlike the others who would have to complete two of the problems.

The third problem was a circuit with three squares in an L shaped configuration. That meant three nodes or junctions (two nodes with three branches and one with four branches), but with six possible loops in total. At least for this one the directions of the currents were already assigned, and all they had to give were the three node equations (instead of just one even for the five branches last time) plus two of the loop equations.

Yesterday’s happenings will be given tomorrow. In the meantime, class dismissed.