The rapid development of science and technology now brings us many types of entertainment wherever you are, anytime. They can listen to music with iPods, watch movies online on tablets or play games on the phone. However, there is a type of entertainment with a long history of development that until today, it still exists as a spiritual food of many people around the world, that is the radio.
Radio machines (radio receivers, radio players, radios) are a familiar item , from children with “good night” program, to adults with news programs or “read late-night stories.” Radio is also a tool for work, such as the driver with the “traffic radio” channel.
Radio waves and radio
Radio waves or radio waves are a form of electromagnetic radiation that has a longer spectrum than infrared light, the frequency from 3 kHz to 300 GHz. Radio waves transmit at the speed of light and in nature, it occurs from lightning.
The radio is also used to refer to a radio (radio) – an electronic device that receives modulated sound waves through an antenna to amplify, restore the original sound and play the sound to the speaker listen. Radios are based on the development of three inventions that are closely related, which are radios, telegraphs, and phones. These three technologies together form a radio technology that was originally called “wireless telegraphy”.
In the history of development, many inventors have tried to apply a variety of wireless signal transmission methods, including electromagnetic induction and signal transmitting methods. However, the radio started with radio wave – a type of electromagnetic wave capable of transmitting music, voice, images and data in the air from one place to another. other places. There are many devices that work by electromagnetic waves including: radio, microwave oven, mobile phone, remote control, television and many other devices. Devices use electromagnetic waves with different frequencies to perform different functions. Radios used in radios have frequencies in the range of 3 Hz (extremely low frequency ELF – Extremely low frequency) to 300 GHz (EHF high frequency band).