Innovative Uses

It's Easy Being Green: Exploring Common Grocery Items with the Vernier Spectrometer

The new Vernier Spectrometer allows students to do a wide variety of new lab investigations. To highlight some of its many capabilities, we walked down to the nearest grocery store and picked up a few products to test. We analyzed the visible light absorbance spectrum of various food colorings to see if we could identify the FD&C dyes used in a popular brand of mouthwash. By comparing the "fingerprint" of the food colorings with the absorbance spectrum of mouthwash, it was easy to determine that the color of the mouthwash was a mixture of blue and yellow dyes, which was confirmed by the information on the label.

To complete our experiment, we mixed a bit of the blue and yellow food coloring solutions to try to mimic the green color of the mouthwash. We matched the color pretty closely, and the activity gave us a theme for this investigation—green liquids.

Next, we tackled some biochemistry. We bought some fresh spinach to add to our salad for a healthy lunch, and saved a few of the leaves. We then chopped up the spinach leaves and soaked them in ethanol for an hour, to extract chlorophyll. By filtering the liquid and diluting it with distilled water, we had our chlorophyll sample. We ran two tests. The first test was similar to the food dye/mouthwash investigation; we measured adsorbance as a function of wavelength. The results are shown to the left. Note the little bump in the graph, just beyond 900 nm. We confirmed it to be caused by the ethanol in the sample.

One final test was done with the chlorophyll solution. Chlorophyll is fluorescent, and we wanted to see if the Vernier Spectrometer could detect it. To test fluorescence, which is light emission rather than absorbance, we removed the light source/cuvette holder from the spectrometer. Then we poured about 2 mL of the chlorophyll solution into a plastic cuvette with four clear sides. We sealed the cuvette with a plastic cap and placed it directly in front of the opening in the spectrometer. By positioning a pen light (also purchased at the grocery store) at a 90° angle to the spectrometer opening, we could not only see the faint orange-red glow of the fluorescing chlorophyll in the cuvette, but the Spectrometer detected it as well. The graph is shown here to the right.

The noisy graph can be attributed to a few factors: primarily that room lights were dimmed but not completely turned off, a plastic cuvette was used (for convenience), and the light source was a fairly wide-beamed white light. The important point here is that with grocery store items and non-quantitative sample preparation, we were able to successfully measure the absorbance spectrum and the fluorescence of chlorophyll.

We wished to continue our chlorophyll investigation, so we wandered along another aisle in the grocery store and selected a couple of types of olive oil. It turns out that part of the color of olive oil is due to chlorophyll. We tested two grades: extra virgin (purported to have the maximum amount of chlorophyll of all grades of olive oil since it is derived from the first pressing of the olives) and light (alleged to contain no chlorophyll). More testing is needed, but our initial results are shown here.

Note that while the olive oil graph has some qualitative similarities to the chlorophyll samples described previously, it is not an exact replication of the chlorophyll absorbance peaks.

Lab write-ups for these activities are available online at www.vernier.com/innovate/spectrometer

Investigating Airport Sound Levels

Anyone who lives along the flight path of a major airport knows that sound pollution is an unpleasant fact of life. Riley Wilson, Tim Horton, and Mario Bautista, 8th grade students at Hughes Middle School in Long Beach, California, know this all too well, often having instruction interrupted as planes fly over their school.

Airplane noise in the Long Beach area is a frequent topic of debate. This motivated Riley, Tim, and Mario to measure the noise level at points along the flight path of Long Beach runway 30 as their science project. Based on their research, they believed that planes landing would create a higher level of sound intensity compared to planes taking off. Equipped with our Sound Level Meters (order code SLM-BTA, $209), they selected locations along the flight path and measured sound level intensities of planes during takeoff and landing. Since the experimental decibel levels exceeded the maximum allowable levels for residential areas, their report has added fuel to the airport noise debate in Long Beach. This has prompted a city councilman to suggest a stricter noise ordinance for the city and has given the boys valuable insight on how science impacts politics.

Note: Riley Wilson is the son of Bill and Margaret Wilson, owners of School Savers, a Vernier and Texas Instruments distributor (www.schoolsavers.com).

Measuring a Plant's Response to Gravity

Judy Day, with the Science House, a NC State University K-12 science outreach program, has developed an activity investigating a plant's response to gravity. Judy uses a ProScope USB digital microscope (order code BD-PSB,$259) to record changes over time in a plant that has been placed on its side. For best results, Judy recommends using an Arabidopsis thaliana (the wild variety) having an inflorescence stem at least 10 cm long. Here is a brief description of Judy's procedure:

Before starting the experiment, place the plant upright, in a dark place for several hours to allow the stem to straighten. Gently mark one centimeter increments on the stem to allow tracking of the changes and to have known reference distances to use for video analysis. Bring the plant to the video location, and with the plant in its upright position, prepare to start the video. Using the time lapse feature of the video software, capture video images every three minutes for a 60 minute period. Gently lay the plant on its side, start the video, and watch the changes. Note: since the plant is sensitive to movement, move as little as possible during the setup.

Once you have your video, use the video analysis features in Logger Pro to measure the changes in the plant as it responds to gravity. The sample graph shows data that Judy obtained. Note the relatively uniform change in stem height over time.

Judy also sent us some suggested extensions to try:

• Compare various points on the stem for movement.
• If the plant has multiple stems, trim the top of one stem and leave the other alone.
• Compare length of stem with range of movement.
• Compare other plants for rates of movement.
• Place the plant in a 4°C environment on its side for an hour; then move the plant to room temperature in an upright position. Record observations of movements of the plant.

Forensics Death Scene Investigation

Students at Susquehanna Township High School in Harrisburg, Pennsylvania, participated in a program where the students studied the life cycle of the blowfly and its relationship to the decomposition of a deer. This program motivated 9th grade student Drew Evans to do some further investigation for his science fair project.

Drew was intrigued with the effect that temperature had on the activity of the insects. Knowing that death scene investigations focus on determining time of death based on body temperature and insect activity and that forensic scientists rely on published temperature readings led Drew to this project. He hypothesized that the actual temperatures at a death scene would differ from temperatures recorded by the local weather agencies.

Drew worked with a local game warden to obtain a deer that had recently been hit by a car. Stainless Steel Temperature Probes were placed around the deer: one under the body, one against the body, and one several feet above the deer (to measure the ambient temperature). Twenty-four hour temperature readings were collected on multiple days with the deer located in different locations. The collected data were compared to the temperatures recorded at the local airport and made available through Penn State's web site. Drew found average differences in temperature ranging between 6.1°F (ambient) to 8.7°F (under the deer), which supported his hypothesis.

This investigation has given Drew a better understanding of the difficulties forensic scientists encounter when estimating time of death. Drew was awarded a gold medal for his first place finish in the Earth Science Senior Division of the Capital Area Science and Engineering Fair (an Intel Regional Science Fair).

Mercury Fingerprint

Did you know that even if a fluorescent lamp is labeled "green" it may still contain some mercury? We used a Vernier Spectrometer to study the emission spectrum of a modern fluorescent tube. It had a very strong peak at 546 nm, one of the characteristic emission wavelengths of mercury. Dispose of your old lamps properly, even if they are marked as "green."

You can also use a cool new Logger Pro feature to compare spectra. There is a mercury spectrum in the Sample Data folder. If you collect an unknown spectrum and want to compare it to a known mercury spectrum, just superimpose the reference mercury data from the Sample Data folder using the new Import from Logger Pro file feature. Do the peaks line up?

Students Monitor Classroom Conditions and Win Awards

Two groups of local science students from Westview High School, Beaverton, OR, recently won honors with projects using our sensors to monitor their school environment.

Julio Montano, Jose Perez, and Josean Perez used our temperature sensors to monitor classroom temperature and how it affects student attention span. The project won awards at the science fair. One of the science fair judges told the Environmental Protection Agency (EPA) about it, and the students were invited to Washington, DC to present their results at a forum.

Josh Goodman, of the Beaverton School of Science & Technology, won the top prize at the local science fair with a project checking the carbon dioxide levels in classrooms, and comparing them to recommended EPA guidelines.

Innovative Uses from the Journals

"Transient Behavior of the Driven RLC Circuit" by Michael C. Faleski, Delta College, Center, MI, in the May 2006 issue of American Journal of Physics explains how he is using LabPros to study RLC circuits powered by a battery in an introductory physics course.

"Teaching about Functions through Motion in Real Time" by Maria L. Fernández, Florida State University, in the February 2006 Mathematics Teacher gives a great explanation of how CBL 2 (or LabPro), along with a Motion Detector, can be used to teach students about functional relationships and the interpretation of graphs.

"Simplifying in the Motion of Coupled Oscillators Using the FFT" by Don Easton, Lacombe, Alberta, in the January 2006 issue of The Physics Teacher describes using LabPro and a Motion Detector to study two pendula connected together via a spring. The Logger Pro FFT feature makes understanding the motion easier.

"Phase-Space Orbits and the Ping-Pong Ball Impact Oscillator" by Peter Millet, James Schreve, and Peter Coxeter, Hamilton College, Clinton, NY, in the February 2006 issue of The Physics Teacher shows how to use Logger Pro and a Motion Detector to study the chaotic behavior of a ping-pong ball driven by a speaker.

"A Rolling Sphere Experiment" by Adam Niculescu, Virginia Commonwealth University, in the March 2006 issue of The Physics Teacher describes a detailed study of the rolling of a ball done through the use of Logger Pro and a Motion Detector.

Send Us Your Innovative Uses!

Do you find yourself reading our Innovative Uses articles and wish you could have your ideas published? Well, you can! Send us your ideas for innovative uses of Vernier data-collection technology, and we might publish your ideas in a future print or electronic newsletter. Entries should include your original data and images of the experiment setup (Images that include students will require signed release forms prior to being published).

If we choose to publish your idea, we will send you a $100 Vernier gift certificate. Send us your ideas today! Submit your ideas to innovativeuses@vernier.com

Looking for More Innovative Uses?

We have over 50 innovative uses using a variety of our products. Your source for ideas of the possibilities with Vernier data-collection technology is www.vernier.com/innovate