USA

The United States of America is a federal constitutional democracy comprising fifty states and a federal region. The country is placed mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie among the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to its east and Russia to the west across the Bering Strait, and the state of Hawaii is in the mid-Pacific. The United States also acquires several territories, or narrow areas, that are spotted around the Caribbean and Pacific.

At 3.79 million square miles (9.83 million km²) and with over 300 million people, the United States is the third or fourth largest country by total area, and third largest by land area and by inhabitants. The United States is one of the world's most culturally diverse nations, the product of large-scale colonization from many countries. The U.S. economy is the largest national economy in the world, with a nominal 2006 gross domestic product (GDP) of more than US$13 trillion (over 19% of the world total).

The nation was founded by thirteen colonies of Great Britain located along the Atlantic seaboard. Proclaiming themselves "states," they issued the Declaration of Independence on July 4, 1776. The insubordinate states defeated Britain in the American innovative War, the first successful colonial war of independence. A federal convention adopted the current United States creation on September 17, 1787; its agreement the following year made the states part of a single republic. The Bill of Rights, comprising ten lawful amendments, was ratified in 1791.

Indicator

Dial indicators are instruments used to correctly measure a small distance. They may also be known as a Dial gauge, Dial Test Indicator, or as a clock. They are named so because the measurement results are displayed in a overstated way by means of a dial. They may be used to check the dissimilarity in tolerance during the check process of a machined part, measure the deflection of a beam or ring under laboratory conditions, as well as many other situations where a small measurement needs to be registered or indicated.

An economic indicator is a statistic concerning the economy. The lighting system of a motor vehicle consists of lighting and signaling procedure mounted or integrated to the front, sides and rear of the vehicle. The purpose of this system is to present illumination for the driver to operate the vehicle safely after dark, to increase the visibility of the vehicle, and to display information about the vehicle's presence, position, size, direction of travel, and driver's intentions concerning direction and speed of travel.

Capacitance

Capacitance is a measure of the quantity of electric charge stored for a given electric potential. The most general form of charge storage device is a two-plate capacitor. If the charges on the plates are +Q and -Q, and V gives the voltage difference between the plates, then the capacitance is given by c=Q/v. The capacitance of the majority of capacitors used in electronic circuits is several orders of size smaller than the farad. The most ordinary units of capacitance in use today are the millifarad (mF), microfarad (µF), the nanofarad (nF) and the picofarad (pF).

The dielectric constant for a number of very useful dielectrics changes as a function of the applied electrical field, e.g. ferroelectric materials, so the capacitance for these devices is no longer purely a purpose of device geometry. If a capacitor is driven with a sinusoidal voltage, the dielectric constant, or more exactly referred to as the dielectric permittivity, is a function of frequency. A changing dielectric constant with frequency is referred to as a dielectric dispersion, and is governed by dielectric recreation processes, such as Debye relaxation.