July 29, 2020
Every semester, roughly 200 students from across the university roll up their sleeves for experimental physics. The course serves not only as the introductory lab course for physics majors but fulfills a general education lab requirement for many students.
When Associate Teaching Professor David Anderson was tasked with moving the course online amid the coronavirus pandemic, his first thought was “how on earth are we going to do this?”
“Sometimes you get so involved in the minutiae of the course that you can’t see the wood for the trees,” Anderson said.
He had to step back and think about not only the learning objectives of the course but also how to adapt those objectives to these new and unprecedented circumstances. A large part of the course focuses on learning on how to analyze data and draw conclusions from experiments, something that was relatively easy to adjust to at-home instruction.
Anderson began by reworking some of the current experiments in the lab. In one experiment, students typically use a system of masses and springs as an example of a harmonic oscillator, a model that appears again and again in physics and in other sciences and can be seen in a number of things from the swaying of a suspension bridge in the wind to the growth of a colony of bacteria.
In the lab, students determine the resonance curve for the oscillator by applying certain driving frequencies and measuring the response of the system.
“One of the key objectives is to have students collect the data in an efficient and intelligent way,” Anderson stated, because it teaches students how to increase scientific value and minimize wasted time and energy. Students must analyze the data as they go along and choose different driving frequencies that will allow them to determine the resonance curve in as few steps as possible.
Anderson replicated this experiment by taking videos of the motion for 50 different driving frequencies. Students can sort through the enormous list by choosing one video, measuring the response and selecting additional frequencies intelligently.
“They can do the same thing online by choosing just the right videos to watch,” Anderson said.
“Rather than watching all 50 of them, which would take them all day, they can go through the right 20 videos and get the results they need efficiently.”
But Anderson admits that to truly meet the goals of the course, students do need some kind of hands-on work.
“With hands-on work, there’s no substitute for doing the experiment yourself — learning how to get a good sense of all of the potential issues and errors that can arise when you do an experiment and how you might go about controlling for those,” Anderson said. Experimental work also teaches students how to document their work by writing procedures, testing hypotheses and analyzing and communicating their results.
Thus, he created new experiments to capture the hands-on elements of the course where students could learn how to set up, conduct, analyze and report a scientifically rigorous experiment.
Running in the footsteps of Galileo, Anderson tasks students with analyzing the motion of objects falling over different distances to determine a precise value for acceleration due to gravity. Using their cell phone’s video camera, students can record the falling object in slow motion and go through the video’s time index to accurately measure its motion.
“Five or 10 years ago, we wouldn’t have been able to do this with any precision from home,” Anderson said.