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The Heat’s On: Physicists Find New Solution to Old Problem

(l-r) Ryan Phillips '16, Tim Gfroerer and Peter Rossi '15
(l-r) Ryan Phillips '16, Prof. Tim Gfroerer and Peter Rossi '15

Using new technology, Professor of Physics Tim Gfroerer and two student researchers have solved an old problem in their field. The paper they wrote about their work, titled "Thermal Diffusivity Imaging," appeared in the American Journal of Physics-a publication that touts itself as the most widely read physics journal in the world.

The experiment involved using a thermal camera to measure the temperature distribution on a metal plate when the plate comes into contact with a glowing-hot metal rod. The experiment is a familiar one to physicists, but results have always been skewed because previous techniques weren't fast enough to overcome the fact that parts of the plate are inevitably cooling while simultaneously parts are heating up.

In summer 2014, Gfroerer and student Peter Rossi '15 decided to revisit the experiment. They wanted to take advantage of the fact that modern thermal cameras are much more affordable, and have a much faster frame rate then earlier models-10 frames per second in their configuration.

During that summer Rossi devised a simple but effective way to heat the plate using a torch with a brass rod, and conducted tests on copper and aluminum plates. The tests seemed to support the mathematical model of the experiment. That was confirmed in spring 2015 when another student researcher, Ryan Phillips '16, analyzed the data. Phillips found that it perfectly matched the theoretical expectation set forth in Fick's Second Law, which describes the diffusion of heat.

Gfroerer said the concept is simple. "Anyone can understand it. We're just ramming a hot rod into a sheet of metal and watching the sheet heat up. Theoretical models describe how the heat should diffuse, and our experimental data matched the results that the computational model said we should get."

Gfroerer noted that the experiment can be easily replicated in other college-level courses, and hopes instructors will incorporate it into their laboratory curriculum.

Thermal camera
The team’s thermal camera captures data for diffusion of heat through metal.

In addition, Phillips said there may be practical applications for the work. He explained, "The experiment models heat flow in aluminum and copper, and those two metals are used as heat sinks in all sorts of electronic devices. The big fins you see inside computers are typically aluminum and copper heat sinks designed to cool off the elements inside. Our method might help engineers characterize those thermal processes."

The three Davidson physicists presented a poster describing their work at a recent zone meeting of the Society of Physics Students. They were delighted to find shortly thereafter that the American Journal of Physics had published it, selecting it as one of just three "featured" articles in the November edition. Gfroerer noted that the publication is quite selective, accepting just 20 percent of manuscripts it receives and publishing only about 10 articles per monthly issue.