These charges and holes are understood in terms of quantum physics.
The building material is most often a crystalline semiconductor.
Through such people as Alexander Graham Bell, Ottó Bláthy, Thomas Edison, Galileo Ferraris, Oliver Heaviside, Ányos Jedlik, William Thomson, 1st Baron Kelvin, Charles Algernon Parsons, Werner von Siemens, Joseph Swan, Reginald Fessenden, Nikola Tesla and George Westinghouse, electricity turned from a scientific curiosity into an essential tool for modern life.
In 1887, Heinrich Hertz discovered that electrodes illuminated with ultraviolet light create electric sparks more easily.
The recognition of electromagnetism, the unity of electric and magnetic phenomena, is due to Hans Christian Ørsted and André-Marie Ampère in 1819–1820.
While the early 19th century had seen rapid progress in electrical science, the late 19th century would see the greatest progress in electrical engineering.
In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it.
Current flow can be understood in two forms: as negatively charged electrons, and as positively charged electron deficiencies called holes.
In June 1752 he is reputed to have attached a metal key to the bottom of a dampened kite string and flown the kite in a storm-threatened sky.
Alessandro Volta's battery, or voltaic pile, of 1800, made from alternating layers of zinc and copper, provided scientists with a more reliable source of electrical energy than the electrostatic machines previously used.