March 21st, 2011
MAGNETIC GENERATOR
It only occurred to me later that I had previously (on my last camping trip) used a flashlight where there was no need to get batteries for. I indeed was intrigued and made a note to myself that when returning to the civilization from the woods I would look into it. Well I never did until now. In the last science class we were asked to carry out the Generator Experiment. We again were provid
ed with all the necessary tools some of which were new and others that we had previously used like the NXT adaptor, NXT motor, and the LabView application. We were handed flashlights where instead of the battery there was a magnetic generator. The generator consisted of a magnet that slid inside a coiled wire which if moved enough would generate enough electricity as to light the bulb in the flashlight. The task of the experiment was to observe and conclude if there is any correlation between the numbers of shakes of the generator (the flashlight) with the voltage output. Through this experiment we are to demonstrate the accuracy of Faraday’s Law which states that alternating the magnetic fluxes through coiled wires we could generate electricity, the faster the change the greater the amount of voltages produced.
EXPERIMENT
We connec
ted the NXT motor with the computer and opened the provided LabView application. Then we attached the voltage probe with the lose wires of the flashlight, the magnetic generator so we can record the currents of electricity that go. For a start we run the application without any shakes so that we could retrieve the baseline data. The data would show the amount of voltage in the flashlight without manipulating it through shakes. After retrieving the baseline data and placing it on an Excel sheet I performed the experiment 5 more times at the same 30 seconds interval but with different shake rhythms. Each time I executed the experiment I had various numbers of shakes: 0, 22, 33, 58, 59, and 76 as I evidently had different voltage measurement. All was recorded on the Excel sheet. Once the experiment was executed I moved on to calculations. As instructed I derived the sum square of the gathered voltage data for every run of the experiment. Then I created a table to demonstrate the findings:
|
# of Shakes |
Sum of the square of the voltages |
|
0 |
0.131294259 |
|
22 |
146.8104 |
|
33 |
106.708698 |
|
58 |
104.8284 |
|
59 |
122.3611 |
|
76 |
173.3937 |
Based on these data I configured a scattered plotted graph to visually see if there is a correlation between the number of shakes and the sum square of the voltages. The following is the plotted graph (because of technical problems I was unable to paste it here, therefore I created a PDF format of it- click to open):
CONCLUSIONS
Clearly we see that there is a linear correlation between the number of shakes and the voltage generated. The higher the number of shakes is, progressively greater the number of voltages. Somehow the first experiment after the baseline does not follow this trend and I believe the reason could be the human error. Other than that I conclude that this experiment demonstrated that the Faraday’s Law is accurate. In a nutshell we can safely assume that the more intense the movement of the shake, therefore the sliding of the magnet within the coiled wire, the higher the number of the voltages generated for electricity. Try it yourself:
http://phet.colorado.edu/sims/faradays-law/faradays-law_en.html