Radio

Radio is the use of radio waves is to carry information, such as sound, by systematically modulating some property of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.

Radio systems need a transmitter to modulate (change) some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation (which can be frequency modulation or phase modulation). Radio systems also need an antenna to convert electric currents into radio waves, and vice versa. An antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual stations to be selected. The electromagnetic wave is intercepted by a tuned receiving antenna. A radio receiver receives its input from an antenna and converts it into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc. Radio frequencies occupy the range from a 3 kHz to 300 GHz, although commercially important uses of radio use only a small part of this spectrum.

Ghetto

A ghetto is a part of a city in which members of a minority group live, especially because of social, legal, or economic pressure. The term was originally used in Venice to describe the part of the city to which Jews were restricted and segregated.

Etymology

The English word ghetto comes from the Jewish area of Venice, the Venetian Ghetto in Cannaregio. However, there is no agreement among etymologists about the origins of the Venetian language term. The Oxford University Press etymologist Anatoly Liberman considers that all the proposed etymologies for the Venetian name are wrong, and suggests a possible connection with German Gasse, Swedish Gata, Gothic Gatwo, meaning street. Among the theories that Liberman rejects are the following: getto (foundry), as ge- and ghe- have very different pronunciations in Italy, and the area would logically have been called "getti", foundries, in the plural; borghetto, diminutive of borgo, meaning little town, a nonspecific term; and the Hebrew word get, a divorce document, with no connection to "a place of forced separation".