1. Telephone
The emergence of the telephone is attributed to Alexander Graham Bell. The principle of early telephones is: the sound of speech is a composite vibration in the air, which can be transmitted to On solids, electrical pulses are transmitted on conductive metals. ?Bell applied for a patent for the telephone in March 1876.
2. Aircraft
The Wright brothers pioneered the flight control system that allows aircraft to fly under control, thus laying the foundation for the practical use of aircraft. This technology is still used in On all planes. The great invention of the Wright brothers changed human transportation, economy, production and daily life, and also changed military history.
3. Electric light bulb
Edison's biggest discovery was to use tungsten instead of carbon as the filament. Then in 1906, General Electric invented a method of making tungsten filament for electric lights. Eventually a cheap way to make tungsten filaments was found, and tungsten filament light bulbs are still in use today.
The biggest problem with light bulbs is the sublimation of the filament. Because the slight difference in resistance on the tungsten wire causes different temperatures, where the resistance is greater, the temperature rises higher and the tungsten wire sublimates faster, causing a cycle in which the tungsten wire becomes thinner and the resistance further increases; ultimately, the The tungsten wire is burned out. It was later discovered that replacing the vacuum with an inert gas could slow down the sublimation of the tungsten wire. Most light bulbs today are filled with nitrogen, argon, or krypton gas.
4. Electric motor
The electric motor uses the principle of the force exerted by the energized conductor in the magnetic field (this is different from the magnetic effect of current, current People's Education Edition ninth-grade physics Clearly separate the two), the person who discovered this principle was the Danish physicist Oersted, who was born on August 14, 1777 in a family of pharmacists in Rudjobin, Langland Island.
5. Steam engine
The world’s first steam engine was the Aeolipile invented by the ancient Greek mathematician Hero of Alexandria in the 1st century AD. ), which is the prototype of the steam engine.
A steam engine is a reciprocating power machine that converts the energy of steam into mechanical work. The emergence of the steam engine caused the Industrial Revolution in the 18th century. Until the beginning of the 20th century, it remained the most important prime mover in the world, and later gradually gave way to internal combustion engines and steam turbines.
A steam engine requires a boiler that boils water to produce high-pressure steam. This boiler can use wood, coal, oil or natural gas, or even combustible garbage as a heat source. The expansion of the steam pushes the piston to do work.
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