Secondary students learn superconductivity from phenomenology Marisa Michelini, Lorenzo Santi, Alberto Stefanel Research Unit in Physics Education University of Udine (Italy)

ottobre ’15Michelini, Stefanel - Superconductivity2 N Context Type of school Site grade N class Phy years h per week age N Students s.y. h driver 1 CurricolarSci. LyceumPordenone /0615teacher 2 CurricolarSci. LyceumUdine /0610teacher 3 CurricolarTech. LyceumUdine /0614Prospective teacher 4 CurricolarTech. LyceumScicli (Ragusa) /0620teacher 5 CurricolarClass. Lyceum Vibo Valencia (Ragusa) /0620teacher 6 CurricolarSci. LyceumComiso (Ragusa) /0629teacher 7 CurricolarSci. LyceumBolzano /0611teacher 8 CurricolarSci. LyceumModena /0612teacher 9 CurricolarSci. LyceumTricarico (Matera) /068teacher 10 CurricolarProfession Sc.Gemona (Udine) /0621teacher 11 CurricolarTech. LyceumUdine /079teacher 12 CurricolarProfession Ist.Gemona (Udine) /0721teacher 13 CurricolarSci. LyceumBolzano /0711teacher 14 CurricolarProfession Ist.Bolzano /075teacher 15 CurricolarTech. LyceumPalermo /0721teacher 16Curricular - Lab IDIFO Sci. LyceumTolmezzo /098teacher 17Curricular - Lab IDIFO Geom. Inst.Milano /099CP-IDIFO teacher 18Curricular - Lab IDIFO Profession Ist.Modena CP-IDIFO teacher 19Curricular - Lab IDIFO Sci. LyceumBolzano /099teacher 20Curricular - Lab IDIFO Tech. LyceumTreviso /099CP-IDIFO teacher 21Curricular - Lab IDIFO Sci. LyceumBolzano /094CP-IDIFO teacher 22Curricular - Lab IDIFO Sci. LyceumMilano /096CP-IDIFO teacher Experimentation performed by teachers in school

ottobre ’15Michelini, Stefanel - Superconductivity3 N Context Type of school Site grade N class Phy years h per week age N Students s.y. h driver 1Project "Maturità" 2008 Sci. LyceumUdine /084Res 2Summer School FM 2009 DifferentUdine /096Res 3Project Guidance Sci. LyceumPordenone /096Res 4Young LACOMAS Sci. LyceumUdine /102Researcher 5Curricular - Lab IDIFO DifferentUdine /114Res 6Curricular - Lab IDIFO DifferentCosenza /114Res 7Curricular - Lab IDIFO Sci. LyceumCrotone /116Res 8Summer School FM 2011 DifferentUdine /116Res 9Summer School Pigelleto DifferentUdine /116Res 10Curricular - Lab IDIFO Sci. LyceumUdine /1212Res/teach 11Curricular - Lab IDIFO Sci. LyceumUdine /139Res/teach 12Curricular - Lab IDIFO Sci. LyceumUdine /13 Res/teach 13Curricular - Lab IDIFO Sci. LyceumUdine /139Res/teach 14Curricular - Lab IDIFO Sci. LyceumTolmezzo (Udine) /1312Res/teach 15Curricular - Lab IDIFO Sci. LyceumMonfalcone (GO) /138Res/teach 16Curricular - PhD Exp Sci. LyceumSalerno /136Res/teach 17Curricular - PhD Exp Sci. LyceumSalerno /136Res/teach 18Curricular - PhD Exp Sci. LyceumSalerno /136Res/teach 19Summer School MP 2013 DifferentUdine Res 20Summer School MP 2014 DifferentUdine Res Research Experimentation performed by researcher or teachers/researcher in school

ottobre ’15Michelini, Stefanel - Superconductivity4 RQ1. The phenomenological exploration of SC levitation can produce a more effective understanding of eltectromagnetic processes? RQ2. The analysis of ideal cases what kind of spontaneous model activate in pupils? RQ3. Are these model modified through a phenomenological exploration? RQ4. Which knots remain open? Rsearch Questions

ottobre ’15Michelini, Stefanel - Superconductivity5 School experimentation in a class of 16 students (18 aged) 12 Tutorial worksheets Pre-post test 10 hours + 2 pre/post test A path on magnetic interaction, magnetic field and flux, magnetic properties of matter, SC: -integrated in the ordinary curruculum -defined in accordance with the class teacher -implemented during the regular school week

A) Magnet-objects interaction B) Interaction of a neodimium magnet and 6ottobre ’15Michelini, Stefanel - Superconductivity Ferromagnetic objects Non ferromagnetic objects Bipolar nature of magnetic field source Para/diamagnetic properties of materials E) Interaction of an YBCO disc and a magnet (T=To and T=TNL) F) Comparison with other interaction: Magnetic properties of a SC Peculiarity of SC levitation G) Exploration of stability of levitation C) Current and magnetic field D) Changes in time of the magnetic field and the EM induction Role of em induction H) Breack down of resistivity Meissner effect as R=0, B=0 The steps of the educational path followed: Eddy corrents in magnet falling on/inside conductor

Michelini, Stefanel - Superconductivity7ottobre ’15 Gervasio M, Michelini M (2010),

A- «Slowed down motion because of the induced current»; «induced currents that repeal the magnet» B- “muffled motion” [it falls as on a pillow] (p<0.01) Q9. A disc magnet, such as that shown in the figure, is falling on a thick layer of Cu. 9.1 Will be influenced the falling motion of the magnet by the presence of the Cur layer? explain C – “Cu have low resistivity then it attracts the magnet more fast” D – “Yes, bust just very few, because Cu is diamagnetic” NA – No answer

9.3. It is possible that for some appropriate geometry of the Cu layer and the magnet, i.e. to a suitable magnet can be realized the situation in which the magnet is stationary and remains suspended above the plate? Explain your answer A.No, the effect in not persistent without change B.No, because R  0 C.NO D. Yes, with an opportune geometry of the systems E.Yes for particular magnet F.Yes, if Fm>Fp P<.01

A: would remain suspended / levitating (in 4 cases: perfect diamagnet) B: The phenomena of repulsion would be stronger C: Yes, why he does not repel the magnet so that would not diminish its speed Would it change anything if you replace the Cu layer with a layer with zero resistance? P<.01

Q10. When a cilindrical magnet falls down inside a conductor tube (i.e a Cu tube), after a brief accelerated phase, it falls down at constant velocity 10.1 How it can be explained the phenomenon? A : Because of the induced electric current B: Due to the generated field and the related resistence C: Presence of the electrical resistence in the tube and related Joule effect  Cu  v(t)  constant D: the conductor, having a resistance, acts on the magnet slowing the fall E: Friction due to the contact of the tube and the magnet NA: No answer P<.05

 Cu  v(t)  costante  YBCO =0  v(t)? Q10. When a cilindrical magnet falls down inside a conductor tube (i.e a Cu tube), after a brief accelerated phase, it falls down at constant velocity It will be change something if the conductor have a null resistance? Explain A: It remain suspended/trapped (no dissipation) B: No Joule effect C: No induced current D: free fall (nothing it is opposed to the falling down NA : No answer P<.05

Induced current 9 cases Diamagnetic properties of Cu motivation Free fall 1 cases 10/16 9/16 1/16 7/16

ottobre ’15Michelini, Stefanel - Superconductivity14 A) B) C) D) E) P<.05

ottobre ’15Michelini, Stefanel - Superconductivity15 Q12. Consider the case in which within a uniform magnetic field is posed a cylinder composed by material whose resistivity is nothing. Draw: 12.1 with a blue pen, the configuration of the resulting magnetic field; 12.2 with a red pen. the possible magnetic dipole of the cylinder. Lines inaltered Lines repelled P<.01

ottobre ’15Michelini, Stefanel - Superconductivity16 10/16 8/16 In 6 cases 4/16 8/16 In 3 cases Less density No deviation

9.2. Represent with opportune vectors the magnetic dipole moments that may eventually be present in the two systems. P<.05

Q10. When a cilindrical magnet falls down inside a conductor tube (i.e a Cu tube), after a brief accelerated phase, it falls down at constant velocity 10.1 How it can be explained the phenomenon?  Cu  v(t)  constant A : Because of the induced electrical current (Sub-chategories): A1) The passagge of the magnet produces a flux variation in the tube. The flux variation cause the induction of an electric current. The induced current generate a field of opposite direction with respect of the first. When the two forces are equal in module the velocity in the motion is constant (1  1) A2) Flux variation, creation of an induced current, that cause the magnet slowing down/that contrast the weight force (3  3) A3) The induced current creates Joule effect  (energy dissipation) (0  4) A4) The magnet motion inside the cylinder produce parasite current and therefore a magnetic field that contrast the accelerated motion (0  1)