News from the Department of Physics
There's a lot happening in the WWU world of physics!
Read our latest news stories and updates.
March 2023: Pulsed Laser
There are other things going on in the department but this quarter Optics Lab is making the news since optics has pretty colors and new experiments. As one part of the final optics lab, we tried to build a TEA (Transversely Excited Atmospheric) laser based on the designs shown in several Youtube videos. We did not get it to work during the lab time period.
However, several of us worked on it a bit more after lab and by the second day of spring break, the laser was working well. A picture of the laser firing is shown at the left. The arcs between the two rods are seen nearly the length of the rods. The very bright arc at the lower right suggests that the rods could be aligned a bit better. The laser beam is invisible (UV) but we can see it as the green/yellow light in the Rhodamine B dye in the upper left of the picture. We could make a dye laser using this design.
February 2023: Color of Light
Optics lab is still going strong. One of our labs studied the colors present in white light. In the picture at the right, white light from two sources is compared. The top band is from an incandescent light bulb and the bottom band is from a white LED. At the very bottom of the picture is the scale in nanometers that is almost too small to read. Our eyes detect light from about 400 nm to about 700 nm - almost the exact range of the LED. The incandescent light has a lot of light produced in the range of 750 nm to 1000 nm - mostly heat energy.
January 2023: Optics and 3D Printing
Winter quarter has started and the optics lab is underway. Mounting hardware for the optics breadboard is usually made of aluminum or steel so it is heavy and rigid. Unfortunately it is also expensive. This quarter, we have started making a number of smaller pieces on the 3d printer. The plastic parts are quick to produce but don't work every situation. Here are two of the ones that worked.
In the picture above at left, a plastic piece sits between the metal rod and the metal mirror assembly. It offsets the mirror so it is directly over the rod. In the picture above at right, a piezo is held in place by a plastic clamp. The clamp attaches to a metal lens holder. Both these pieces allow us to spend less time setting up experiments and more time doing the experiment.
December 2, 2022: Martin Scott
With great sadness we mark the passing of Martin Scott who was killed today in a traffic accident.
Marty has been a part of the Physics Department for many years. He taught Astronomy to hundreds of Walla Walla University students for more than twenty years. When the Kretschmar Hall observatory was completed in 1999, Marty was its first daily administrator. While teaching astronomy and running the observatory, he completed a Masters Degree in Astronomy. He then became the "astronomy guy" to the entire Walla Walla valley contributing to astronomy programs in all three colleges, the local newspaper, and a host of smaller projects.
A student was looking for Marty some time ago and couldn't remember his name. The student came into my office and asked "Where is the professor that looks like Santa Claus and knows about stars?" As I think back over the ways Martin Scott has touched our lives over the years, I will always remember him as the "Santa Claus who knows about stars."
Tom Ekkens, Chair of Physics, Walla Walla University
November 2022: Projectiles
Fall is here but leaves aren't the only thing falling to the ground. Projectiles are launching into the crisp fall air and falling back to earth as part of labs in all of the introduction classes. In the picture at left framed by colorful trees, the Conceptual Physics Lab students are launching rocket-shaped projectiles and measuring their range as a function of angle.
October 2022: Telescope View Events
With the vibration damping improvement from the tuned mass damper and the clear skies provided by a late summer drought, this has been our best quarter for viewing ever. Jupiter was at its closest approach in decades and Saturn was also in a prime viewing location. We got in the following groups before the fall rains started:
September 15, Faculty and staff. M13, Jupiter, and Saturn.
October 1, Students in Conceptual Physics, General Physics, and Principles of Physics. Jupiter, Saturn, M13, M31, and the moon.
October 12, All of WWU as announced in the 11am daily email. Again Jupiter, Saturn, M13, M31, and the moon.
October 22, Parents Weekend. Jupiter, Saturn, and M13. The clouds came up during the viewing so the season is over now.
September 2022: Telescope TMD
As mentioned back in December of 2021, the telescope is mounted on a metal pier that reaches down through the third story of Kretschmar and shakes like a leaf in the wind. The December vibration reduction update added air legs between the pier and the telescope. It did reduce vibration a bit but added tracking problems. During the past two months, the air legs were removed from the system and a tuned mass damper (TMD) was added. As shown in the picture, the TMD is mounted near the top of the pier and is made of 6 lead bricks floating on sorbothane. The major vibration peaks at 6 and 10 Hz have a reduction of about 5 dB in each axis.
August 2022: Raspberry Pi Physics
Summer is also the time when new experiments are developed and new equipment is built. This summer Dr. Ekkens has been working on incorporting Raspberry Pi boards into several experiments. In the picture is the Pico board. This $4 board has a fast processor and several analog inputs which make it a good fit for a collecting data and controlling hardware. Students in General Physics this coming year will use it for at least one lab.
August 2022: Conferences and Travel
During the summer between the junior and senior year, we strongly encourage the physics majors to participate in a Research Experience for Undergrads (REU). A number of universities and labs participate in the program so most majors are able to enjoy this learning opportunity. This summer we have one major and one minor doing research at different universities. In addition to research, students and faculty are able to participate in conferences. Both Dr. Campbell and Dr. Ekkens are attending conferences this summer. As COVID restrictions continue to wane some conferences now have in-person options.
July 2022: Classes and Camps
The summer is underway with lots of activities. Dr. Campbell is teaching General Physics in the highly compressed summer option. Cramming three quarters of material into the summer doesn't leave students much time for anything else. Dr. Ekkens hosted a section of science camp where area school children learned about sound and light. Everyone - even the camp staff - enjoyed taking thermal imaging pictures of themselves. The Tesla coil was also a noisy hit.
June 2022: A new Raman Spectrometer
Raman Spectroscopy is a topic that we cover very heavily in Nanotechnology (and a bit in optics). We have two older Raman spectrometers that we have been using for lab but we really have needed a third one based on the number of students in lab. This year we bought one that is quite different from the two we already have. It is green (532nm) instead of IR (985 nm) and it is sold as a number of discrete components instead of a single box. Fortunately, a plastic file folder box is about the right size and we were able to zip-tie the components in place as shown in the picture at the left. It will be interesting over the next few years of labs to see which wavelength works the best with our carbon nanotube samples.
June 2022: Graduation
This graduation will go down in memory as the time we almost got washed out. During the service, we had only a few rain showers come through. Later in the afternoon the rain really arrived and we got 1 inch of rain in about 12 hours. The picture shown at the right is during the ceremony just before the first drops of rain fell. In the physics department we had one major graduate this year.
May 2022: Solar Cells
The quarter of Physical Electronics lab is coming to an end. We have made a lot of devices in lab this quarter - pn junctions, SBDs, Hall probes, and two types of transistors. Most of them worked, but the prettiest of them all was a solar cell. The picture shows a 2 mm view of the cell without any changes to the color. The surface of the cell is totally dry but looks like oil on water.
April 2022: New Oscilloscopes
We are just finishing up an upgrade to our oscilloscopes used in the General Physics and Principles of Physics laboratories. These new oscilloscopes replace the older passive matrix displays so they are much brighter. This upgrade also moves us from generic parts to name brand parts so the reliability of the equipment is better and the noise is lower.
March 2022: Ferrofluids
The quarter of Nanotechnology is finishing up this month. Our next-to-last lab covers magnetism so we looked at the unique shapes we could make in the fluid with magnets - both permanent and electro. This year we set a local record from the amount of mess made with ferrofluid. This picture was taken a few minutes before "the event."
February 2022: Nanotubes
This year we got better pictures of carbon nanotubes that we ever have before using our PVC STMs. The picture at the right shows at least three tubes across the image from the lower left corner to the upper right corner. The diameter of the smaller tubes is about 5 nm or 1000 times smaller than a red blood cell. Best resolution on the STM appears to be 2 nm.
January 2022: PVC STM
It is once again Winter quarter so the PVC scanning tunneling microscopes are being built by the Nanotechnology class. New for this year is a better holder for the borescope and a new power supply for the amplifiers. The power supply is shown in the picture at the left. It is based off a bipolar kit from Jameco and is housed in a 3d-printed box. The new power supply replaces four 9-volt batteries for the amplifiers and a small 12-volt supply for the motor. So far there doesn't seem to be difference in performance between the power supplies apart from ease of use.
December 2021: Telescope Vibration
The telescope is mounted on a metal pier that reaches down through the third story of Kretschmar and bolts to a cement cross bar that is part of the floor of the third story. The pier and all of the third story are vibrating which blurs out the images seen with the telescope. Over Christmas break, the vibration at the telescope was characterized and air legs were added between the top of the pier (the gray piece in the picture) and the telescope (the black piece in the picture). These air legs reduce the vibration seen in the image by about 50%. Further work will be done during the summer to isolate the telescope even more.
November 2021: Chaos in Electrical Circuits
This quarter, our upper division physics majors are taking Experimental Physics. We are spending time learning to program data acquisition boards. For the lab this week, we built a circuit from a function generator, inductor, and diode. The circuit exhibits chaotic behavior so we used our programming skills to collect the voltage across the diode as a function of drive voltage. The resulting logistic map at the right shows the pitchfork bifurcations typical of chaotic systems. We were able to compute Feigenbaum's number from this graph with fairly good accuracy. Taking this data by hand would have taken forever but using the computer, the picture was constructed in about 5 minutes.
October 2021: Speed of Light Lab Extension
In Modern Physics lab, we measure the speed of light. Two years ago the experimental method was changed to incorporate 3d-printed parts to hold the laser, mirror, and detector. This hardware allows us to measure path lengths up to 40 meters with a computed speed within 3% of the accepted value. This year we added a new challenge. We bought TOSLINK fiber optic cables and using the 3d-printed parts shown in the picture are able to connect cables together to get a path length of 25 meters. This experiment allows us to see that light travels slower in material.
September 2021: Classes are starting.
September 27: Classes are starting today and we are back to in-person classes and labs. Just before the first physics class of the quarter, this rainbow was visible over our observatory. In addition to the rainbow, this should be an exciting year in physics and astronomy. The world is awaiting the launch of the James Webb Space Telescope on December 18. This telescope will have almost 10 times more collecting area than Hubble and more than 250 times the collecting area of our 16" telescope mounted in the silver dome on the roof of Kretschmar Hall.
August 2021: Summer Research
Summer is the time for research in the physics department. Several of our majors are working on projects at other locations and one is working here. The Raman project continues again this summer with Stefan working on the software aspect of the project. Felicia worked on the project last and got most of the hardware tested so now getting the software to make all the hardware work together is the job. In the picture, the Raman controller is on the left screen and the troubleshooting documentation is on the right two monitors.
July 2021: New Equipment
Summer is the time that we buy new equipment and test it out. This summer we are upgrading our Zeeman Effect experiment. The initial hardware was put together by Calvin, a physics major several years ago, from spare parts. This summer we bought the dedicated system from Pasco shown in the inset of the picture. In the last few weeks, testing on it has been completed and it will be used in the Modern Physics Lab this coming fall. The split lines, shown in the picture, are from the unpolarized light.
June 2021: Graduation
This school year has come to a close. Graduation has occurred - but was a bit strange due to the virus restrictions. There were four graduation ceremonies to limit the total number of people at each one. The picture is at the right was taken at the 8:30am Sunday graduation. Masks and physical distancing didn't prevent the participants from having an "almost normal" celebration. We are proud of our three physics graduates and wish them the best in graduate school.
May 2021: Telescope Camera
After the previous viewing in April, a new telescope camera was purchased. The previous camera was about 20 years old, connected to a computer using a parallel part, and was water-cooled. This new camera is USB 3.0 and is air cooled so it is much easier to use. The first images taken with the new camera were of the moon. While the telescope mount lets too much vibration through, several good pictures were obtained.
April 2021: Telescope Lab
The physics majors and the General Physics lab students used telescopes in the observatory and on the observation deck to view the moon and mars. The red light everywhere in the picture of us standing around the 16" telescope is better at preserving night vision. Since the moon was full, it really dominated the sky.
March 2021: Sodium Doublet
This month, we finished up the optics labs for the quarter. One of the improvements this time was in measuring the sodium doublet. Sodium emits light in two wavelengths that are close together (called the doublet). There are several methods to measure the difference in the two wavelengths but some of them require more complicated tooling or are difficult to set up. The picture shows our method for using an interferometer to measure the difference in wavelengths. The improvement was to level the system using a laser shown by the red line and then rotate only a single mirror to the sodium light shown by the yellow line. This geometry made setting up the experiment much easier.
February 2021: Electrifying Labs
General Physics has moved into the Electricity section of the course. The day we used the Van de Graaff generator was also one of the coldest, driest days of the winter. A number of students showed impressive electron repulsion by making their hair stand on end. Miranda took a break from answering student questions about the lab to demonstrate this impressive hair style.
January 2021: We are back!
The physics department is back in session with 50% of the classes taught in person this quarter. As seen in the picture of our optics lab, we are wearing masks and face shields, but we are once again doing the lab experiments that make our graduates stand out of the crowd. During the last two COVID-19 quarters, we covered all the labs by video but it just isn't the same as being there.
December 2020: Christmas Carols on a Tesla Coil
Here are some Christmas Carols played on our singing Tesla coil for you to enjoy this holiday season. Sorry about the focus drifting around during the songs. I need to redo it sometime with the focus fixed.
November 2020: Ball Bearing Crystals
In Modern Physics, we talk about how the Braggs used x-rays to determine crystal structure. In lab, we don't use x-rays because of radiation damage. Instead we duplicate the classic experiment using low-power microwaves with "crystals" made of ball bearings. Usually we hold the bearings in position using foam as seen in the picture on the right. This year (after the lab was completed using foam holders), we started building up ball bearing holders using plastic. The plastic does mess up the microwaves a bit, but it allows us to change the crystal size really fast. The crystal on the left has holes cut for bearing spacings of 3, 3.5, 4, and 4.5 cm. A laser engraver was used to make the pieces. In time for next year's lab, we will have a number of these sets made.
October 2020: Projectile Motion with remote learning.
Normally during October we have labs in all the big classes where we take air rockets out to the field and learn about projectile motion. Since all those classes are on-line this quarter and it doesn't seem fair to have a fun lab with no students invited, we did a lab on projectile motion based on shooting a ball from a spring. Because the ball only goes about 2 meters - instead of the 65 meters for the rockets - the lab is a lot less exciting, but it does give much better results. In the graph, the rocket data is all over the place because we have to deal with wind, variation in launch pressure, and human uncertainty in identifying the exact landing location. The ball data is almost a perfect parabola since taking the data via video in a room without wind minimizes many of the noise sources. (In the graph, the ball distance data was multiplied by 30 so both data sets fit on the same graph.)
Moral: Distance learning isn't as fun but it can be more accurate.
September 2020: School is back in session.
School is back in session for the 2020-2021 year. Because covid-19 is still with us, many of the sophomore and junior classes are remote. General Physics and Principles of Physics are on-line so the labs are mostly done by watching videos of the experiments. In the picture at the left, we are measuring the height of Kretschmar Hall by dropping a golf ball from the top and measuring its time of flight. One advantage of the video lab is that the camera is much more accurate with timing than a human using a stopwatch.
August 2020: Spectra Program
In a number of labs from Conceptual Physics all the way to Modern Physics, we look at spectral lines from various gasses. Normally, the data is analyzed on the same program that was used to collect the data. During the remote learning last quarter, it became obvious that not all students had the necessary hardware to run the main program so they couldn't analyze the data fully.
July 2020: Fluke Donation
This summer the Physics Department gratefully received a donation from the Fluke Corporation. The multimeters and thermocouple therometers will be used in the large introductory labs such as General Physics and Principles of Physics. The Fluke Corporation routinely makes such donations to colleges in the Northwest. Thank you.
June 2020: Dark Matter
Sometimes when looking at news items like this article on dark matter, https://www.cnet.com/news/dark-matter-detector-picks-up-unexpected-and-unexplained-signal/, one might click on the link to the original article, https://arxiv.org/pdf/2006.09721.pdf. This article is a bit more interesting than some because one of the authors/researchers is a graduate from the Physics Department at Walla Walla University. Darryl came back to WWU and gave a talk about this experiment several years ago. It is exciting to see the progress that the team is making.
May 2020: Physical Electronics Lab
While our labs are still on-line for the quarter, we are continuing to see improvements in data collection by using cameras as I mentioned last month. So far this quarter, we have gotten excellent data for the thermal expansion of metal tubes in General Physics and Principles of Physics Labs and in the temperature dependence of semiconductors in Physical Electronics Lab. Also in Physical Electronics Lab, we set a department record for the most voltage generated by a solar cell that we built. In the picture at right, the cell is in the upper right of the picture with all the gold "fingers" making electrical contact to it. While 0.183 V may not seem like much compared to the 0.5 V that a commercial cell generates, it is much better than the 0.025 V that our previous build process produced.
April 2020: On-Line Labs
This quarter, Walla Walla University like nearly all other schools is meeting on-line only. Our labs are on-line as well. This means the experiment is recorded and the students watch the video and collect data from the video. In the picture at left, a screen capture from a Principles of Physics lab is shown. A stream of electrons is hitting some helium gas and making the greenish glow. From the measured parameters, we can compute the ratio of the electron charge to the electron mass.
The interesting thing is that using cameras to collect data in many situations gives better results than the data collected by eye only. Some labs are being rewritten to suggest that the data be collected by cameras always.
March 2020: Covid-19 and Physics
Most universities in the US (and many around the world) are on-line only starting this month to limit the spread of Covid-19. Walla Walla University is among that number which means the WWU Physics Department is working on ways to delivery lab classes remotely. While there is some variation in our labs, our basic idea is to record a video of the experiment being run. The video will allow the students to collect the data from the equipment and to do the analysis steps as normal. The only missing step from doing the lab in person is the setting up of the equipment. While we realize this is inferior to the hands on approach, it is the best solution we have right now.
February 2020: Graphene
For another experiment in nanotechnology, we have been working with graphene. This experiment starts with graphene oxide in water. The solution is put on a piece of filter paper and allowed to dry. Once it is dry, it forms an insulating brown layer. Then we expose part of the layer to light and convert the graphene oxide into graphene which conducts. This allows us to draw circuits on the paper as shown in the picture.
January 2020: Nanotechnology
The new quarter has started and Introduction to Nanotechnology is underway. The first two labs of the quarter are spent building a scanning tunneling microscope. As shown in the picture PVC and hot glue play a role in the construction. Four lab groups are each building up their own microscope. The detailed build directions from the 2014 article are available at https://www.wallawalla.edu/academics/areas-of-study/physics/faculty/ekkens-research/studentstm/ . Over the last six years, we have made several changes in the design to make use of our 3d printers. An update to the build directions should be finished by this summer.