Today was a strange and tough start to the week. A tragedy occurred last night evening (around 7:30PM) at a very popular outdoor site in our area. I’m thinking about what has come to be known as the Trestle Trail Bridge Shooting. I will not go into the details, but will mention that four people were killed and a fifth is in critical condition. While the family affected did not attend our schools, the children did attend a parochial school in our city and the Trestle Trail connects our community and it’s neighbor. Nearly everyone in the community knows the area and has been there. We did not talk about it in my classes, but it was there in many minds including mine. My thoughts and prayers go out to the families involved.
We started the class by discussing how to use an analogue (panel) meter t measure electrical potential difference (or voltage). We just measured the potential difference across individual cells, then the cells ‘end-to-end’, two cells ‘side-by-side’, and finally in a cell holder (it was interesting to watch the students struggle to figure out how to use only two cells in the holder and to get he maximum potential difference). Here are a few photos:
If you look closely at the meter, you will see I have added a label, electrical potential difference, in J/C, to remind the student exactly what the ‘voltage’ and volt mean.
From there we built the simplest circuit… one cell, one wire, and one bulb. I ask hem to get it to light two different ways and that simply switching the cell ends does not count. This activity is one of the more famous ‘electrical tasks’, even discussed in the documentary Minds Of Our Own. It is interesting to me that several of our engineering and manufacturing academy students will say almost immediately that it cannot be done.. two wire need to be used, but the other students will just dig in and give it a try. I like this task because it introduces circuits and how a simple bulb is wired, that the bulb does not ‘care which direction the charge moves through it. Tomorrow more circuits, with electrical potential difference readings taken while the circuit is functioning.
We discussed the energy test they took on Friday and then had a brief introduction to the next unit, electrical concepts here too. They were sent home with the task of answering the 7 Charge questions.