On Thursday 17th March the School of Mathematics and Physics welcomed 14 A-level physics students from William Farr School for the afternoon. After an impromptu tour of the campus they were treated to a lecture by Dr Fabien Paillusson, “Does Mr. Entropy need Phoenix Wright?”
Fabien first outlined the historical development of the concept of entropy by discussing thermodynamics, the ‘arrow of time’, and entropy as a measure of ‘disorder’, before presenting the more contemporary interpretation that entropy is related to the amount information ‘missing’ from a system. Entropy is a notoriously difficult concept to grasp and it was absolutely fantastic to see the students following Fabien through to his conclusions.
After a short break Dr Danilo Roccatano gave a lecture on electromagnetism. Starting with an 11th century Chinese compass, Danilo gave an excellent historical overview of the key figures in the development of electromagnetism, from Alessandro Volta and Hans Christian Ørsted to James Clerk Maxwell and Michael Faraday. The significance of several of the ground-breaking experiments which played a role in the development of electromagnetic theory, for example Millikan’s oil drop experiment, was also explained.
Finally, the students were asked to perform a group experiment to determine if the electron charge has a constant value as Millikan’s results suggested. A beam of high energy electrons was directed perpendicularly through the variable magnetic field produced by a pair of Helmholtz coils. The resulting deflection of the electrons, which was measured by the students, is proportional to the magnetic field strength and the specific charge of the electron. It was a relief when the students verified that the electron charge is indeed a constant and that the laws of physics still apply in our new lab!