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.

Surname

A surname or family name is a name added to a given name. In many cases, a surname is a family name and many dictionaries define "surname" as a synonym of "family name". In the western hemisphere, it is commonly synonymous with last name because it is usually placed at the end of a person's given name.

In most Spanish-speaking and Portuguese-speaking countries, two or more last names (or surnames) may be used. In China, Hungary, Japan, Korea, Madagascar, Taiwan, Vietnam, and parts of India, the family name is placed before a person's given name.

The style of having both a family name (surname) and a given name (forename) is far from universal. In many countries, it is common for ordinary people to have only one name or mononym.

The concept of a "surname" is a relatively recent historical development, evolving from a medieval naming practice called a "byname". Based on an individual's occupation or area of residence, a byname would be used in situations where more than one person had the same name.

Brandenburg Concertos

The Brandenburg Concertos by Johann Sebastian Bach (BWV 1046–1051, original title: Six Concerts à plusieurs instruments) are a collection of six instrumental works presented by Bach to Christian Ludwig, Margrave of Brandenburg-Schwedt, in 1721 (though probably composed earlier). They are widely regarded as some of the best orchestral compositions of the Baroque era.

History

Bach wrote out the music himself for presentation to the Margrave rather than leaving it to a copyist. While he took the opportunity to revise the music, most likely, it was not freshly composed. He appears to have selected the six pieces from concertos he had composed over a number of years while Kapellmeister at Köthen, and possibly extending back to his employment at Weimar (1708–17).

Bach's dedication to the Margrave was dated 24 March 1721. Translated from the original French, the first sentence of Bach's dedication reads:

Bach's reference to his scoring the concertos for "several instruments" (Concerts avec plusieurs instruments) is an understatement. Bach used the "widest spectrum of orchestral instruments … in daring combinations," as Christoph Wolff has commented. "Every one of the six concertos set a precedent in scoring, and every one was to remain without parallel." Heinrich Besseler has noted that the overall forces required (leaving aside the first concerto, which was rewritten for a special occasion) tallies exactly with the 17 players Bach had at his disposal in Köthen.

G major

G major (or the key of G) is a major scale based on G, with the pitches G, A, B, C, D, E, and F♯. Its key signature has one sharp, F♯.

G major's relative minor is E minor, and its parallel minor is G minor.

For orchestral works in G major, the timpani are typically set to G and D, a fifth apart, rather than a fourth apart as for most other keys.

Notable compositions

Baroque period

Classical era

List of compositions by Johann Sebastian Bach

There are over 1000 known compositions by Johann Sebastian Bach. Nearly all of them are listed in the Bach-Werke-Verzeichnis (BWV), which is the best known and most widely used catalogue of Bach's compositions.

Listing Bach's compositions

The earliest lists of Bach's compositions are given by his biographers, starting from his obituary which gives a list of instrumental works printed during the composer's lifetime (from Clavier-Übung I to The Art of Fugue), followed by a list which groups other types of compositions he wrote. The first separately published biography of the composer, by Johann Nikolaus Forkel, follows the same setup: its ninth chapter first lists printed works (adding four-part chorales that were published in the second half of the 18th century), followed by a rough overview of the unpublished ones. In the first half of the 19th century more works were published, so the next biographies (Schauer and Hilgenfeldt in 1850) had more elaborate appendices listing printed works, referring to these works by publisher, and the number or page number given to the works in these publications. So, for example, the Prelude and Fugue in E-flat major can be indicated as "C. F. Peters Vol. III No. 1", or any of the variants ("Griepenkerl and Roitzsch Vol. 3 p. 2", "Peters Book 242 p. 2", "P. S. V., Cah. 3 (242), No. 1", etc.)