As human beings, we have been aware of static electricity for hundreds of years. This form electricity is a transfer of electrons (sub-atomic particles which carry electrical charge) as a result of friction. For example, if you rub a balloon on your clothing it will “stick” to a wall. Secondly if you rub a glass rod on your clothing and hold it next to a gentle stream of water from a tap the water stream will be pulled toward the rod. The early and neolithic humans were doubtless aware of electricity in the form of lightning.
The Battery and electric lighting
The technical term for a battery is an electrochemical cell and their invention is credited to the Italian scientist Alessandro Volta. He demonstrated that electricity could be harnessed by demonstrating that it could be made to flow through a conducting wire. The wire glowed further indicating that electrical energy could be transferred into light energy. By the middle of the 18th century the first circuits using electricity derived from electrodes standing in water had been developed.
The first practical application of using circuits to transmit electricity was electric lighting. Concurrently, this was made possible by the invention of the first functioning incandescent light bulbs by Thomas Edison. Many other inventors and scientists were aware of the concept but on October 22nd 1879 the first functioning bulb remained functioning for 14 hours.
Battery powered circuits
The early circuits were powered by batteries which produced a steady and constant flow of current from negative to positive terminals. This direct current (DC) always flows in the negative positive direction; the issue was that the electricity could not be transported over long distances. In fact for these early circuits any area exceeding about a square mile would present problems.
To the Engineers, scientists and proto-electricians of the time, the potential was obvious, but they could not overcome the distance issue. A Serbian engineer known as Nikola Tesla developed and applied the notion of an alternating current (AC). This current, as the name suggests, constantly changes and can be made to change direction and it changed everything.
How alternating current changed everything
If the electrical current is alternating the voltage level in a given circuit can be changed by a device known as transformer. The flow of electrical current always produces a magnetic field and so in a DC circuit the field does not change but in an AC circuit the field oscillates in tandem with the current.
Transformers work by a physical science principle known as magnetic induction, which can only occur in an AC circuit. In essence Nikola Tesla invented a method by which the voltage magnitude of a circuit can be increased enabling long distance transmission of electricity. Quite literally, the rest as the colloquium goes, is history.
The above introduction shows, that there are many devices which can cause an electrical discharge, but electricity as a form of energy is useless to us, without circuits.