The Experimental and Historical Foundations of Electricity (vol. 2)

Description

This work deals with the most fundamental aspects of physics. The book describes the main experiments and discoveries in the history of electricity. It deals with attractions and repulsions, positive and negative charges, conductors and insulators, electrification by friction/contact/induction, the triboelectric series, electrification of adhesive tapes, distribution of charges in conductors, electric equilibrium and the instrument which indicates potential difference, electric shielding, the power of points, sparks and electric discharges in air, electrets and the temporal preservation of the electrification of bodies, the mysterious non-electrostatic forces, etc. This work explains how to build several instruments: versorium, electric pendulum, electroscope, charge collector, circuit tester, electrophorus, the Leyden jar and capacitors, etc. All experiments are clearly described and performed with simple, inexpensive materials. These experiments lead to clear concepts, definitions and laws describing these phenomena. Historical aspects are presented, together with relevant quotations from the main scientists. A large bibliography is included at the end of the work.

Portuguese version PDF, hard copy, and video review

cf. André Assis's International Conference of Hands-on Science July 20, 2021, talk (slides) demonstrates the simple experiments by Stephen Gray, Du Fay, et al.:

Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years.