Conceptions of secondary students on phenomenology of superconduction

1. Marisa Michelini, Lorenzo Santi, Alberto Stefanel Research Unit in Physics Education, DCFA, University of Udine - via delle Scienze 206, 33100 Udine, Italymarisa.michelini@uniud.it, Lorenzo.santi@uniud.it, alberto.stefanel@uniud.it Introduction Teaching and learning Modern Physics is a challenge for Physics Education research (PE 2000; AJP 2002, Meijer 2005; Johanson, Milstead 2008; Steinberg, Oberem 2000). Nowadays superconductivity can be brought in the educational laboratory both for qualitative exploration, both measurements with sensors interfaced to the computer. In the context of a research project to renew physics curricula introducing modern physics, an educational path for high school was developed to introduce superconductivity, integrating it in the courses of electromagnetism. The educational path implement an IBL approach using a set of hands-on/minds-on apparatuses designed with simple materials and High Technology (Kedzierska et al. 2010; Michelini, Viola 2011), YBCO samples, USB probe to explore R vs T (Gervasio, Michelini 2010). The rational of the path on Meissner effect for HSS Students School experimentations 1) YBCO disc at T=Te: no magnetic properties 2) YBCO at T=TNL: evident levitation of a magnet magnetic properties? 3) Systematic exploration of the interaction of the SC with different magnets and different objects (ferromagnets in primis), with different configurations  It always shows repulsive effects close to a magnet: an YBCO at TTNL is diamagnetic. 4) The interaction between SC and a magnet do not depend on the pole put close to the surface of the magnet, the equilibrium position is always the same.. 5) The SC tends to react to an external magnetic field creating a counter field to maintain B=0 inside (Meissner effect). Research experimentation summary: 14 sites (all around in Italy) 1199 students of 220 classes (last two grade of the Italian High School) Explorative activities (informal learning) 4 contexts, with 715 students) 6) The magnet would be stopped just falling over a conductor with R=0   B=0 Meissner effect 7) Experimental measurement R vs T at phase transition Conceptions of secondary students on phenomenology of superconduction From the test: High School Experimentation in Udine-Salerno-Tolmezzo 122 students (13 grade – 18 aged) 10) From the model of conduction to the model of superconduction: analysis of the energy of the electrons inside of a crystal lattice and Cooper pairs formation 11) persistent currents and pinning effect and the correlated phenomenology (i.e. magnetic suspension, the MAGLEV train model). Discussion The students use concepts as field lines, magnetization vector, EM induction, as tools to construct a link between magnetic and electric properties of a SC, describing the phenomenology of the Meissner effect, according to the suggestion of many authors (Essen, Fiolhas 2012). In the phenomenological description of the SC the aim is the recognition of the role of the EM induction. How this state is produced or the phase transition occurs, it is described as results of creation of the Cooper pairs. From research experimentations carried out in different contexts emerges that the majority of students recognize the change in the magnetic properties of the SC under Tc, the B=0 condition, the different nature of the magnetic suspension and the levitation of a magnet on a YBCO. Tutorials From the tutorial (N=240): according to the observations carried out, which aspects characterize the Meissner effect? A) Existence of Tc and/or repulsion/levitation (21%) B) diamagnetism of YBCO (B=0); B line do not cross the magnet; YBCO screens the magnetic properties) in more than half of cases also Tc (38%) Pre/post test C) R=0, and exist Tc (15%) D) B=0 and R=0 (13%) NA: not answer (12%)