Electricity and Ohm's Law

A Wednesday and Friday holiday reduced electricity to an introduction to Ohm's Law and the power relationship.

Monday's introduction had to be done without the microhydroelectric example from the MicSem video Power Comes in Many Forms.

Power was $0.1885 per kilowatt hour at the last buy prior to class. By the next day power was up at $0.22 per kWh. 

As I did in the spring I ran with a shared folder of photos from Drive. I think having at least one prop would help ground this in the physical world. The photos do not make clear that labels are usually on the bottom.


This particular appliance recently stopped working.


Wednesday the local cold hit. Thursday was going to be a low energy lab. Focused on Ohm's law. Batteries and bulbs was dropped. Conduction was dropped. The focus was on the new Ohm's law gear.


The procedure was modified to use only a single digital multimeter. This meant changing the wiring to measure current and voltage. While this increased wear and year on the multimeters, there was the upside that the constant swapping into and out of the circuit reinforced that voltage is across a load, current is measured inline. 


Another upside is that the resistors were 100 and 330 Ohm's, this is much easier on the batteries. The old rig required using 7 Ohms to get a current that could be read on the analog ammeter.


330 Ohm resistor 

Emleen, Siniann, and Rindy. 

The new equipment seems to be even more engaging than the older equipment. 

With the new equipment, everyone in the group can see the values. The old equipment required sitting optically aligned with the deflection needle.

Stella. Memechin, Ian

Coed groups have a gender based equipment differential. Men wind up with the equipment, women take notes. This happens elsewhere as well, but in a traditional society with male traditional chiefs, there is even more of a tendency for females to give way to males in a physical science laboratory. 

Pevirleen, Renae, and Mia working five batteries. The lab uses the same technique to vary the voltage as the earlier variant: increase the number of batteries. There are potentiometers, but then those become a mysterious black box that is harder to explain than more batteries.


Pevirleen, Renae

The rig at five batteries and a 200mA current DCA setting. 


Alyssa, Ivy, Leriangelica

Alyssa records data while Ivy and Leriangelica work with the circuit.




Jarden setting up a three battery circuit.


Lonie "Ney" enters data. 

The lab went well and has a clearer sharper focus in this format. I know none of the reports will get confused by what to do with the batteries and bulbs material. That has been a source of confusion in the past. Elimination of batteries and bulbs along with conduction makes the lab a tad short. Perhaps a second experimental rig with two resistors in series should be added as a part two. 

Comments

Post a Comment

Popular posts from this blog

Plotting polar coordinates in Desmos and a vector addition demonstrator

Image
In an earlier post I noted that Desmos did not directly plot polar coordinates. Not only was I incorrect, but Desmos responded to my blog to correct me! Although I had at some point seen that one could define a function f(x)=3x+5 and then have Desmos calculate f(6), I had not absorbed how this might be used to plot polar coordinates. The above works beautifully . Realizing that I could effectively program Desmos, I applied this thinking to demonstrating how to add two vectors when given the magnitudes m and the direction angles theta. The graph calculates the i and j components for the two vectors and then adds the vectors, graphically displaying the result while also providing information on the magnitude and direction of the vector sum. m1 and theta1 are the magnitude and direction angle for one of the two vectors, m2 and theta2 are the magnitude and direction for the other vector. All four are dynamically interactive and can be changed. The diagram purports to illustra...
Read more

Traditional food dishes of Micronesia

Image
Clara, Jennette, and Joanie presented ground hard taro cooked in an umw, effectively a hot rock oven. Pohnpeian: rotama. Pingelapese: sero. Mwoakillese: rodma. Mortlockese: Amahd. Kosrae: rodoma. After cooking in an umw the rotama is pounded with the petiole of a palm frond. Rotama is made from hard or swamp taro, known as mwahng on Pohnpei, mweian on Pingalap, pula in Mortlockese, and pahsruhk on Kosrae. In traditional times on the outer islands the women had primary responsibility for tending the taro while the men handled fishing and climbing tasks. Joesen and Noeleen presented fermented breadfruit from the outer islands of Yap such as Woleai and Eauripik. The raw ingredients were actually brought in from Yap, Noeleen prepared the maare.  The leaf wrap is ti leaf - Cordyline fruticosa. Pauleen, Barnson, Trisha, Verginia, Con-ray, and Maylanda from Kitti, Pohnpei brought in mahi umw, koahpnoair koakihr, and uht sukusuk. Above is breadfruit umw, mahi umw, o...
Read more

Setting up a boxplot chart in Google Sheets with multiple boxplots on a single chart

Image
The  Google Statistics  add-on for Google Sheets can display multiple boxplots in a single chart. The key is the layout of the data. One column should be the variable by which the data is to be grouped, the other column should be the data to be box plotted. Set up the Statistics add-on with the data to be plotted as the variable, and the grouping column as the "by" variable. In this image I had deselected all but the boxplot option, the result was the appearance of the Moment, Standard errors, and Confidence intervals options. The default is apparently a 95% confidence interval for the mean. The result is multiple boxplots on a single chart with a common scale. The new tab that is created also quotes 95% confidence intervals for the mean. Note that as of 2018 the Google Statistics add-on cannot be found by search in the add-ons. In addition, as of May 2018 the add-on no longer verifies, possibly due to the add-on not having been updated since August 2017. One may ha...
Read more