Electricity is indispensable in modern society. Today, man could hardly live without this energy. Suppose, for example, electrical power plant is off for a month. We can imagine the damage to the economy that relies on electricity and the discomfort of the life of modern man. The importance of electricity invaluable.
But let’s make some investigations of electricity. First, let’s dig up a little of its history. The Greek philosopher, Thales of Miletus, is said to have first observed electric charges. But there was little advances in this area from that time. Let’s jump to the beginning of what is called the Industrial Revolution. Historians of science say that Industrial Revolution began around 1760. Since then until now, it is divided into four periods. (However, as to the bracketing of the period, it appears to be somewhat flexible. There are some variations as to the exact time a phase of an Industrial Revolution began.)
The first Industrial Revolution is said to have spanned from 1760-1850. In this period, there were remarkable inventions. James Hargreaves invented the spinning jenny (1764). James Watt invented the steam engine (1769). Eli Whitney invented the cotton gin (1793). Robert Fulton made the first steamboat (1807). England opened the first public railway (1825). Samuel Morse invented the telegraph (1844).
However, it was during this period that the law of electromagnetic induction was discovered (1831) by Michael Faraday. He made a disc apparatus to generate electricity. But a practical generator was developed later.
The second Industrial Revolution is said to have spanned from 1850-1914. In this period, there were remarkable developments. Henry Bessemer made the first mass production of steel (1856). The US completed the first transcontinental railroad (1869). Alexander Graham Bell invented the telephone (1876). Thomas Edison developed his Direct Current (DC) generator, or dynamo, in the 1870s; he invented the incandescent bulb in 1879. Karl Benz developed the first automobile run by petrol (1885). The Wright brothers made their first powered flight in 1903. Henry Ford introduced his first Model T car (1908).
Nikola Tesla developed his Alternating Current (AC) generator and induction motor in 1887. The AC generator is the one now used in electrical power plants around the world. It is because AC electricity can be transmitted over long distances.
The third Industrial Revolution is said to have spanned from 1914 to early 2000s. Key developments in this period were the following. Stainless steel was found in 1916. Short-wave radio was invented in 1919. Polaroid photography was invented in 1932. Frequency Modulated (FM) radio was invented in 1933. The first nuclear bomb was successfully tested on July 16, 1945, the kind of bomb dropped on Hiroshima in WWII. The transistor was invented on Dec. 23, 1947. It is a revolutionary invention, for it becomes the basis of the digital technology we have today.
Texas Instruments developed the first transistor radio (1953). Jack Kilby invented the microchip (1958), the foundation of modern computers. Theodore Maiman invented the laser (1960). Douglas Engelbart invented the computer mouse (1964). US military developed the Internet (1969). Microprocessor was introduced in 1971. Steve Jobs and Bill Gates popularized the personal computer (1975). Motorola introduced the first handheld cell phone (1983). Microsoft introduced the Windows Operating System (1985). Tim Berners-Lee developed the World Wide Web (WWW) in 1991. The Global Positioning System (GPS) became widely available for civilian use in 2000.
The fourth Industrial Revolution is said to have begun in mid-2010s to the present. It has gained momentum beginning this period. It is characterized by revolutionary developments in technology, such as AI, IoT, robotics. Automation, smart factories emerged in this period. Quantum technology is emerging. These developments have great impact on global economy.
However, these technologies that emerged in the third and fourth Industrial Revolutions depend largely, or wholly, on electricity. Without electricity, these technologies would be dead objects.
Now back to electricity. There are several energy sources for generating electricity. They can be classified into two types: non-renewable and renewable energy sources. Under non-renewable energy sources are the coal, natural gas, petroleum and nuclear energy. They are non-renewable because they cannot be replaced quickly after being used up. Coal, natural gas, petroleum and nuclear energy are used as fuels in generating electricity. In particular, nuclear energy comes from nuclear fission, splitting of the atom. It produces enormous amount of energy according to Einstein’s equation, E=MC^2, where E is the energy produced, M is the mass, and C is the speed of light squared (300,000 m/s)^2. This means a little amount of mass would produce an enormous amount of energy. For example, it is said that the bomb dropped on Hiroshima contained 64 kg of uranium but only less than one gram was converted into energy that burned the place down to the ground (except for a Jesuit convent that remained standing though only roughly one kilometer from the epicenter).
Under renewable energy sources are the solar, wind, geothermal, ocean tide, hydrogen, ocean thermal energy conversion. They are renewable because they are naturally replenished. Solar energy directly comes from sunlight. Wind rotates wind turbine. Hydropower turns water wheel. Geothermal comes from the ground usually near a volcano. Biomass comes from plants, animals and microorganisms. Ocean tide utilizes tides to drive a generator. Hydrogen is combined with oxygen to produce power. Ocean thermal energy conversion utilizes the difference of the temperatures between the surface (hot) and the depth of the ocean (cold).
The AC generator developed by Nikola Tesla is the one commonly used to generate electricity. It is driven by some of the energy sources mentioned above. These energy sources are crucial in generating electricity. They deserve presentation of their basic principles of operation for the benefit of the public, especially students.