Why did Tesla make his coil in the first place? Do they have any practical purposes?
Tesla built his first oscillator as a tool for studying high-frequency electrical phenomena. Practical applications for this type of electrical power supply include a form of high-efficiency, high-frequency lighting ballast. It can be used to power fluorescent and incandescent lamps, as well as high-frequency arc lamps. The carbon button incandescent lamp can be lit with only one connecting wire. He also developed a single-wire electric motor. His work with the single terminal incandescent lamp led him to investigate the generation and physical properties of X rays. Tesla’s more advanced tubes differ from typical X-ray tubes in that they have no target electrode and produce X rays through vacuum high-field emission and a process known as Bremsstrahlung. Tesla’s oscillator can be used to power a device for the production of ozone and to induce a reaction between oxygen and relatively inert nitrogen, producing gaseous nitrogen oxides. It can also be used as a wireless transmitter, being
