ELECTRONICS

Television, stereophonic recording and play back, the computer, robots, and space probes are all products of electronics. Electronics is the branch of physics concerned with the generation and behavior of electrons, as in transistors and electron tubes. It is especially concerned with their use in electronic devices, in which electricity is used to control, communicate, and process information. These devices have caused greater changes in everyday life than those of any other technology introduced in the 20^th century.  

The basic of electronics Is the electronic signal, an electric current that represents information. There are two basic types of electrical signals: analog and digital. In Analog signals, some continuously variable aspect of the electrical current represents the information. In amplitude modulated (AM) radio transmissions, for example, the amplitude, or strength, of the electromagnetic radio wave is proportional to the amplitude of the signal- the volume of the sound that the radio wave carries. The greater the amplitude of the radio wave, the louder the sound that radiates from the radio speaker.

In contrast, digital signals use standardized pulses to represent numbers. With a digital audio signal, the amplitude of the signal for a set amount of time is converted to a number represented by, for example, 16 pulses of fixed duration and amplitude. The audio signal as a whole is transmitted as a series of such 16-pulse codes.

Most electronic devices use digital signals. In these signals the numbers are almost always represented in binary code; that is, instead of using a number system based on 10, as is used in writing numbers and manual arithmetic, electronic system use writing numbers based on 2. There are only basic numbers in this system: 0 and 1, with 1 being represented by pulse and 0 by the absence of a pulse, or some similar arrangement.  

Taken from: Encyclopedia Britannica students’ library, incorporated.2006