Study of the electrical properties of matter began in the first half of the 18th century, and mainly concerned the investigation of visually striking phenomena such as sparks, electrical discharges and lightning.
Electrostatics, the study of matter’s electrical properties, had an important place in 19th century teaching demonstrations. Electrical charges, produced by electrostatic friction devices and stored in Leyden jars, could be transferred to variously shaped conductors to produce spectacular effects.
The French scientist Charles-Augustin de Coulomb (Angoulême, 1736 – Paris, 1806) laid the basis of the mathematical understanding of electricity, formulating a law on forces of interaction between electrical charges discovered using the torsion balance, an instrument he devised.
The invention in 1800 of the Voltaic pile, by Alessandro Volta (Como, 1745 – Comnago Volta, 1827), making electric current available continuously, led to the flourishing of research on electrical conduction in materials and on the effects produced by current; at the same time, batteries were designed with electrodes of various types and immersed in different acids, to overcome the drawbacks of the Volta’s battery and to obtain ever higher voltages. Teaching laboratories acquired various types of battery, electrical resistors and capacitors.
The discovery, in the 1820s by Christian Oersted (1777-1851) of the interaction between electric currents and magnetic fields and that of electromagnetic induction by Michael Faraday (1791-1867) in 1831, led to the invention of a great many socially significant technological applications.
Into the physics teaching collection came electromagnets, electric motors, electric bells, the telephone and telegraph for pupils’ education.
Practical applications of discoveries concerning electrical phenomena led to the vertiginous development of technology, starting from the mid-nineteenth century but especially in the 1890s.
Industrial progress, linked to the use of electricity as a driving force, required ever higher current intensities and voltages. The electro-mechanical industry has also had to face problems connected with measuring the energy used, designing and building reliable, precise meters so as to guarantee its correct billing. The technical requirements necessary to ensure the insulation and correct operation of switches, commutators, rheostats, fuses etc. had to be adapted to new demands, but were also constrained by the historical and economic circumstances of the period.
In the years between the First and Second World Wars, the Autarky laws imposed the use of economic materials. Marble, slate and wood were substituted by cheaper substances such as Bakelite – a lightweight synthetic resin of high electrical resistance.
Switches, commutators, fuses, current meters, etc. they were shown to students to demonstrate advances in science and technology.