The inventions and explorations of mankind in the 20th century are as follows:
1, X-rays
X-rays are a kind of electromagnetic wave with extremely short wavelength and great energy, and X-rays are shorter than the wavelength of visible light (about 0.001-10 nanometers, and the wavelength of X-rays used in medicine is about 0.001-0.1 nanometers), and the photon energy of X-rays is several tens of thousands to hundreds of thousands times larger than the photon energy of visible light. energy is tens to hundreds of thousands of times larger than that of visible light. It was discovered by German physicist W.K. Roentgen in 1895, so it is also called Roentgen ray.
The x-rays have a high penetrating ability, and can penetrate through many substances that are opaque to visible light, such as ink and paper, wood, and so on. This invisible rays can make a lot of solid materials visible fluorescence, so that the photographic negative sensitization and air ionization and other effects. x-rays were initially used for medical imaging diagnostic and?x-ray crystallography. x-rays are also free radiation and other such rays that are harmful to the human body.
2, aircraft
Aircraft (aeroplane, aircraft) is a power plant with one or more engines to generate forward thrust or pull, by the body of the fixed wing to generate lift, in the atmosphere, the flight of the heavier-than-air aircraft. Airplanes are the most common type of fixed-wing aircraft. According to the type of engine they use, they can be categorized as jet airplanes and propeller airplanes.
The airplane is one of the most significant inventions of the early 20th century and is recognized as having been invented by the American Wright brothers. Their flight on December 17, 1903 was recognized by the Federation Internationale de l'Aeronautique (FAI) as "the first controlled, sustained power flight of a heavier-than-air aircraft," and in the same year they founded the Wright Aircraft Company.
3, air conditioning
Air conditioner (Air Conditioner). Refers to the use of artificial means, the building / structure of the ambient air temperature, humidity, cleanliness, flow rate and other parameters to regulate and control the equipment.
Generally includes cold source/heat source equipment, hot and cold media transmission and distribution systems, end devices and other auxiliary equipment. Mainly includes, refrigeration host, pumps, fans and piping systems. The end device is responsible for the use of cold and heat from the transmission and distribution, specific treatment of the air state, so that the target environment of the air parameters to meet the requirements.
4, credit card
Credit card (Credit Card), also known as credit card. It is a way to pay for non-cash transactions and is a simple credit service.
Credit cards are certificates of credit issued by commercial banks or credit card companies to credit-qualified consumers. Consumers with credit cards can shop or spend money at specialized commercial services, which are then settled by the bank with the merchant and the cardholder, who can overdraw up to a specified limit.
5, computer
Computer (computer), commonly known as computer, is a modern electronic calculator for high-speed calculations, can be numerical calculations, but also logical calculations, but also has a memory function. It is able to run according to the program, automatic, high-speed processing of large amounts of data of modern intelligent electronic equipment.
By the hardware system and software system is composed of, without installing any software computer called bare metal. Can be divided into supercomputers, industrial control computers, network computers, personal computers, embedded computers, five categories of more advanced computers are biological computers, photonic computers, quantum computers and so on.
Baidu Encyclopedia-Computer
Baidu Encyclopedia-Credit Card
Baidu Encyclopedia-Air Conditioner
Baidu Encyclopedia-Airplane
Baidu Encyclopedia-X-rays