Magnetically Controlled Reflection of a Ferrofluid Cell



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Figure 20 – A bar magnet under the cell, showing red, yellow, and brown lines.



Figure 21 – Ferrofluid cell readings using the 45 degree incidence channel.

Keeping in mind that 45 degree incidence channel showed that the yellow and brown lines have the same peak reading at around 650 nm, lets look at he shoulders of the of yellow and brown lines. Figure #21 is a zoomed in version of Figure #19, notice that yellow line reading has more green wavelengths than the brown line reading at around 550nm.


The yellow line and the baseline share the same spectrum features and the red and brown lines share some features. This will become important at the end of the document. I will show that each yellow line shares the same polarization. We can already see that all the lines share 90 percent of the spectrum readings and the only real difference is small amount of blue and green frequencies.
One interesting thing is that none of these colors are pure colors, the yellow line only appears yellow because of the RGB mixture of many frequencies. This is same trick that our cameras and computer monitors use to represent composite colors


Figure 22 – Ferrofluid cell readings using the 90 degree incidence channel.
In Figure #22 we see the light that made it to the aluminum surface mirror and exited the system at 90 degree incidence. The data shows that yellow lines require less total deflection of the incoming light than the redlines. This makes sense that if the photons are showing up in the 45 degree incidence channel, then it must be missing from the 90 degree channel.

Third Experiment: I went to my local dollar store and obtained some consumer grade dye filters. These filters are normally used for the lighting effects of parties and garage bands. The first thing I did was to take spectrum transmission readings using my incandescent light source, show in Figure #23.
The names I used for the filters is based on the colors of the plastic that makes up each filter, and does not necessarily predict their transmission profiles. For example the green filter and the blue filter overlap considerably in their spectrum transmission wavelengths. All the filters passed portions of the infrared spectrum which turns out to be a good sanity check on the data.


Figure 23 - Spectrograph transmission readings of four color dye filters

All the spectrum readings of Figure #23 were taken in the same session with the same integration times. In other words, the data is scaled correctly so we can compare both amplitude and frequency.


The rest of the spectrum readings in the third experiment are reflection readings with the light source at -45 degrees and the spectrum probe 6 millimeters away from the ferrofluid layer at zero degrees normal. Both the camera and fiber optic probe have the same orientation, and all the spectrum readings share the same integration times and are scaled correctly. All the photographs, and color channels of the photographs, share the same f5 f-stop and 1/13 of second exposure times with minimal processing.

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