EMDemos

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Demonstrating Electricity and Magnetism

A mainstay of the course Electricity & Magnetism that I taught in Fall 2014 were the nearly dozen demonstrations that were studded throughout the span of the course. It was a real pleasure building these demonstrations, and refining the subtleties while maintaining their direct visual appeal. Thanks to our technical staff in the Physics Lab (Hafiz Rizwan, Khadim Mehmood, Azeem Iqbal, Afshan Jamshaid), who elegantly materialized my ideas as we slowly build an impressive array of demonstrations all supplied with pictorial procedures and in most cases, video recordings to help teachers replicate these ideas in their own teaching.

My underlying philosophy of including demonstrations inside the classroom has always been quite simple.

My first goal is to make students remember physics. The Confucian adage from 250 BC, “Tell me and I will forget; show me and I may remember; involve me, I will understand” adds new dimensions to the already complicated teaching and learning exercise but highlights the role of visually appealing practical demonstrations and here I am not talking about computer simulations but real experiments.

Second, I always want to emphasize in my courses that physics (and science) is not an encyclopedia of facts, rather it’s a process of discovery fueled by experiments which are, after all, the final arbiters and progenitors of some of the greatest physical insights into our understanding of our world. Practical experiments, therefore, offer a glimpse into the scientific method that relies on scientific inquiry, imagination, and occasionally the failed but fortuitous accidental discoveries made inside the laboratory. Demonstrations, especially modern versions of the historic experiments performed by none others but the likes of Gauss, Faraday, Oersted and Tesla show that the development of our ideas on electromagnetism doesn’t happen in fits and starts, rather it’s an evolutionary accumulation and we being students of physics in a city in Pakistan—the developing world—don’t have to always feel like a hapless island but are part of a civilizational mainland and temporal continuum. We may be dwarfs but can definitely stand on the shoulders of giants (and can hence look further ahead).

Demonstrations that were shown in the course included:

magnetic braking, falling magnets in metal pipes, modern versions of Oersted's discovery from the 1820's, charging by induction, ionic winds, levitating superconductors, demonstrating electric fields inside metallic conductors, temperature dependence of resistances, heating a light bulb by immersing in liquid nitrogen, charging and discharging of capacitors, hearing microscopic magnetic domains, forces on conductors, motional emf, Curie point of ferromagnets, and electromagnetic induction.

--Muhammad Sabieh Anwar, 2014

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