How Mankind Did Get Introduced to Electricity?
Electricity is all around us. In addition to running through the wires of our homes, it’s in the clouds in the sky, in the static sparks in our flannel pajama pants, and even running through our bodies in our hearts, brains, and nervous systems. Long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE referred to these fish as the “Thunderer of the Nile”, and described them as the “protectors” of all other fish. Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians.
Several ancient writers, such as Pliny the Elder and Scribonius Largus, attested to the numbing effect of electric shocks delivered by catfish and electric rays, and knew that such shocks could travel along conducting objects. Patients suffering from ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Possibly the earliest and nearest approach to the discovery of the identity of lightning, and electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning (raad) applied to the electric ray.
Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with cat’s fur to attract light objects like feathers. Thales of Miletus made a series of observations on static electricity around 600 BCE, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing. Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. According to a controversial theory, the Parthians may have had knowledge of electroplating, based on the 1936 discovery of the Baghdad Battery, which resembles a galvanic cell, though it is uncertain whether the artifact was electrical in nature.
Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber. He coined the New Latin word electricus (“of amber” or “like amber”, from ἤλεκτρον, elektron, the Greek word for “amber”) to refer to the property of attracting small objects after being rubbed. This association gave rise to the English words “electric” and “electricity”, which made their first appearance in print in Thomas Browne’s Pseudodoxia Epidemica of 1646.
Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray and C. F. du Fay. In the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. 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. A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature. He also explained the apparently paradoxical behavior of the Leyden jar as a device for storing large amounts of electrical charge in terms of electricity consisting of both positive and negative charges.
In 1791, Luigi Galvani published his discovery of bioelectromagnetics, demonstrating that electricity was the medium by which neurons passed signals to the muscles. 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. The recognition of electromagnetism, the unity of electric and magnetic phenomena, is due to Hans Christian Ørsted and André-Marie Ampère in 1819-1820; Michael Faraday invented the electric motor in 1821, and Georg Ohm mathematically analysed the electrical circuit in 1827. Electricity and magnetism (and light) were definitively linked by James Clerk Maxwell, in particular in his “On Physical Lines of Force” in 1861 and 1862.
While the early 19th century had seen rapid progress in electrical science, the late 19th century would see the greatest progress in electrical engineering. 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, becoming a driving force of the Second Industrial Revolution.
In 1887, Heinrich Hertz discovered that electrodes illuminated with ultraviolet light create electric sparks more easily. In 1905 Albert Einstein published a paper that explained experimental data from the photoelectric effect as being the result of light energy being carried in discrete quantized packets, energizing electrons. This discovery led to the quantum revolution. Einstein was awarded the Nobel Prize in Physics in 1921 for “his discovery of the law of the photoelectric effect”. The photoelectric effect is also employed in photocells such as can be found in solar panels and this is frequently used to make electricity commercially.
The first solid-state device was the “cat’s-whisker detector” first used in the 1900s in radio receivers. A whisker-like wire is placed lightly in contact with a solid crystal (such as a germanium crystal) in order to detect a radio signal by the contact junction effect. 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. These charges and holes are understood in terms of quantum physics. The building material is most often a crystalline semiconductor.
The solid-state device came into its own with the invention of the transistor in 1947. Common solid-state devices include transistors, microprocessor chips, and RAM. A specialized type of RAM called flash RAM is used in USB flash drives and more recently, solid-state drives to replace mechanically rotating magnetic disc hard disk drives. Solid state devices became prevalent in the 1950s and the 1960s, during the transition from vacuum tubes to semiconductor diodes, transistors, integrated circuit (IC) and the light-emitting diode (LED).
Electricity is a form of energy caused by those tiny, negatively-charged particles known as electrons. When electricity builds up in one place, scientists call it static electricity. When it moves from one place to another, it’s called current electricity. Electric currents power all of those electronic devices we’ve come to depend on. To form an electric current, electrons must flow steadily along a closed path known as a circuit. Circuits usually consist of electrical components connected with wires. The wires and other parts of a circuit are usually made of metals, such as copper or aluminum, which are good conductors of electricity.
Metals conduct electricity because their atomic structure is such that they have free electrons that allow electricity to flow easily through them. Materials with atomic structures without free electrons don’t allow electricity to flow freely. Scientists call these materials insulators. Rubber is a good example of an insulator. Current electricity can be further divided into two types depending upon how it moves around a circuit. If the electrons always move around the circuit in the same direction, that’s called a direct current (DC). On the other hand, if the electrons constantly reverse direction at the rate of 60 times per second as they travel around the circuit, that’s known as alternating current (AC).
Batteries produce a direct current. Electricity always flows in the same direction between the positive and negative terminals of the battery. In general, batteries produce a current at a fairly low voltage, which is a measure of the force pushing the electrons around the circuit.
By way of comparison, the electricity that flows from a power plant to the outlets in your house is alternating current. Alternating current can be generated at extremely high voltages and transmitted over large distances. A series of transformers lowers the voltage of the electricity before it gets to your outlets, so it can be used by the large appliances and electronic devices in your house. Despite the fact that it can indeed be dangerous when misused, alternating current revolutionized the world to the point where we can’t live without it today!