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166-458: A headlamp is a lamp attached to the front of a vehicle to illuminate the road ahead. Headlamps are also often called headlights , but in the most precise usage, headlamp is the term for the device itself and headlight is the term for the beam of light produced and distributed by the device. Headlamp performance has steadily improved throughout the automobile age, spurred by the great disparity between daytime and nighttime traffic fatalities:
332-467: A bottle or hub dynamo . The first horseless carriages used carriage lamps, which proved unsuitable for travel at speed. The earliest lights used candles as the most common type of fuel. The earliest headlamps, fuelled by combustible gas such as acetylene gas or oil, operated from the late 1880s. Acetylene gas lamps were popular in 1900s because the flame is resistant to wind and rain. Thick concave mirrors combined with magnifying lenses projected
498-402: A grow light to aid in plant growth especially in indoor hydroponics and aquatic plants with recent research into the most effective types of light for plant growth. Due to their nonlinear resistance characteristics, tungsten filament lamps have long been used as fast-acting thermistors in electronic circuits. Popular uses have included: In Western culture, a lightbulb — in particular,
664-577: A lower house based on population; and the Senate , an upper house based on equal representation for each state. Federalism provides substantial autonomy to the 50 states, while the country's political culture promotes liberty , equality , individualism , personal autonomy , and limited government . One of the world's most developed countries , the United States has had the largest nominal GDP since about 1890 and accounted for over 15% of
830-581: A monochromatic orange-yellow light, which gives a similarly monochromatic perception of any illuminated scene. For this reason, it is generally reserved for outdoor public lighting applications. Low-pressure sodium lights are favoured for public lighting by astronomers, since the light pollution that they generate can be easily filtered, contrary to broadband or continuous spectra. Many lamp units, or light bulbs, are specified in standardized shape codes and socket names. Incandescent bulbs and their retrofit replacements are often specified as " A19 /A60 E26 /E27",
996-528: A parabolic reflector . Using principles of reflection, the simple symmetric round reflective surface projects light and helps focus the beam. There was no requirement in Europe for headlamps of standardized size or shape, and lamps could be designed in any shape and size, as long as the lamps met the engineering and performance requirements contained in the applicable European safety standards . Rectangular headlamps were first used in 1960, developed by Hella for
1162-580: A " Special Relationship " with the United Kingdom and strong ties with Canada , Australia , New Zealand , the Philippines , Japan , South Korea , Israel , and several European Union countries ( France , Italy , Germany , Spain , and Poland ). The U.S. works closely with its NATO allies on military and national security issues, and with countries in the Americas through
1328-506: A common size for those kinds of light bulbs. In this example, the "A" parameters describe the bulb size and shape within the A-series light bulb while the "E" parameters describe the Edison screw base size and thread characteristics. Common comparison parameters include: Less common parameters include color rendering index (CRI). Life expectancy for many types of lamp is defined as
1494-414: A complete ban on incandescent bulbs would contribute 5 to 10 billion euros to the economy and save 15 billion metric tonnes of carbon dioxide emissions . Halogen lamps are usually much smaller than standard incandescent lamps, because for successful operation a bulb temperature over 200 °C is generally necessary. For this reason, most have a bulb of fused silica (quartz) or aluminosilicate glass. This
1660-414: A consortium of state motor vehicle administrators standardized upon a system of two 7 in (178 mm) round sealed beam headlamps on all vehicles—the only system allowed for 17 years. This requirement eliminated problems of tarnished reflectors by sealing them together with the bulbs. It also made aiming the headlight beams simpler and eliminated non-standard bulbs and lamps. The Tucker 48 included
1826-542: A coordinated, continent-wide military effort. Finally, deteriorating relations between the British military establishment and the colonists, relations that were already less than positive, set the stage for further distrust and dislike of British troops. Following their victory in the French and Indian War, Britain began to assert greater control over local colonial affairs, resulting in colonial political resistance ; one of
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#17327867502271992-534: A decentralized government that operated until 1789. After the British surrender at the siege of Yorktown in 1781 American sovereignty was internationally recognized by the Treaty of Paris (1783), through which the U.S. gained territory stretching west to the Mississippi River, north to present-day Canada, and south to Spanish Florida . The Northwest Ordinance (1787) established the precedent by which
2158-484: A defining "cyclops-eye" feature: a third center-mounted headlight connected to the car's steering mechanism. It only illuminated if the steering was moved more than ten degrees off center and the high beams were turned on. A system of four round lamps, rather than two, one high/low and one high-beam 5 + 3 ⁄ 4 in (146 mm) sealed beam on each side of the vehicle, was introduced on some 1957 Cadillac, Chrysler, DeSoto, and Nash models in states that permitted
2324-400: A distribution of light designed to provide forward and lateral illumination, with limits on light directed towards the eyes of other road users to control glare. This beam is intended for use whenever other vehicles are present ahead, whether oncoming or being overtaken. The international ECE Regulations for filament headlamps and for high-intensity discharge headlamps specify a beam with
2490-410: A downward/leftward bias to show the driver the road and signs ahead without blinding oncoming traffic. Headlamps for right-traffic countries have low beams that "dip to the right", with most of their light directed downward/rightward. Within Europe, when driving a vehicle with right-traffic headlamps in a left-traffic country or vice versa for a limited time (as for example on vacation or in transit), it
2656-483: A few areas, illegal to drive above this speed at night. Some countries require automobiles to be equipped with daytime running lights (DRL) to increase the conspicuity of vehicles in motion during the daytime. Regional regulations govern how the DRL function may be provided. In Canada, the DRL function required on vehicles made or imported since 1990 can be provided by the headlamps, the fog lamps , steady-lit operation of
2822-407: A few prominent industrialists , largely by their formation of trusts and monopolies to prevent competition. Tycoons led the nation's expansion in the railroad , petroleum , and steel industries. The United States emerged as a pioneer of the automotive industry . These changes were accompanied by significant increases in economic inequality , slum conditions , and social unrest , creating
2988-638: A founding member of the World Bank , Organization of American States , NATO , and the United Nations , as well as a permanent member of the UN Security Council . The first documented use of the phrase "United States of America" is a letter from January 2, 1776. Stephen Moylan , a Continental Army aide to General George Washington , wrote to Joseph Reed , Washington's aide-de-camp , seeking to go "with full and ample powers from
3154-435: A gas, such as fluorescent lamps , and LED lamps , which produce light by a flow of electrons across a band gap in a semiconductor . The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting
3320-422: A glass or silica envelope containing two metal electrodes separated by a gas. Gases used include, neon , argon , xenon , sodium , metal halides , and mercury . The core operating principle is much the same as the carbon arc lamp, but the term "arc lamp" normally refers to carbon arc lamps, with more modern types of gas discharge lamp normally called discharge lamps. With some discharge lamps, very high voltage
3486-437: A left- or a right-traffic low beam by means of a two-position bulb holder. Because wrong-side-of-road headlamps blind oncoming drivers and do not adequately light the driver's way, and blackout strips and adhesive prismatic lenses reduce the safety performance of the headlamps, some countries require all vehicles registered or used on a permanent or semi-permanent basis within the country to be equipped with headlamps designed for
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#17327867502273652-598: A period of heightened, overt racism following Reconstruction, a time often called the nadir of American race relations . A series of Supreme Court decisions, including Plessy v. Ferguson , emptied the Fourteenth and Fifteenth Amendments of their force, allowing Jim Crow laws in the South to remain unchecked, sundown towns in the Midwest, and segregation in communities across the country , which would be reinforced by
3818-488: A prominent leader in the early 1960s. The Great Society plan of President Lyndon Johnson 's administration resulted in groundbreaking and broad-reaching laws, policies and a constitutional amendment to counteract some of the worst effects of lingering institutional racism . The counterculture movement in the U.S. brought significant social changes, including the liberalization of attitudes toward recreational drug use and sexuality . It also encouraged open defiance of
3984-619: A renowned physicist and GE consultant, reported to the GE lamp department on successful experiments with fluorescent lighting at General Electric Co., Ltd. in Great Britain (unrelated to General Electric in the United States). Stimulated by this report, and with all of the key elements available, a team led by George E. Inman built a prototype fluorescent lamp in 1934 at General Electric 's Nela Park (Ohio) engineering laboratory. This
4150-526: A sense of manifest destiny . The Missouri Compromise attempted to balance the desire of northern states to prevent the expansion of slavery into new territories with that of southern states to extend it, admitting Missouri as a slave state and Maine as a free state. It further prohibited slavery in all other lands of the Louisiana Purchase north of the 36°30′ parallel . As Americans expanded further into land inhabited by Native Americans,
4316-614: A sense of American identity as well. Men who otherwise never left their own colony now traveled across the continent to fight alongside men from decidedly different backgrounds but who were no less "American". British officers trained American officers for battle, most notably George Washington ; these officers would lend their skills and expertise to the colonists' cause during the American Revolutionary War to come. In addition, colonial legislatures and officials found it necessary to cooperate intensively in pursuit of
4482-612: A sharp, asymmetric cutoff preventing significant amounts of light from being cast into the eyes of drivers of preceding or oncoming cars. Control of glare is less strict in the North American SAE beam standard contained in FMVSS / CMVSS 108 . High beam (main beam, driving beam, full beam) headlamps provide a bright, center-weighted distribution of light with no particular control of light directed towards other road users' eyes. As such, they are only suitable for use when alone on
4648-632: A status solidified after its involvement in World War I . After Japan 's attack on Pearl Harbor in December 1941, the U.S. entered World War II . Its aftermath left the U.S. and the Soviet Union as the world's two superpowers and led to the Cold War , during which both countries struggled for ideological dominance and international influence . Following the Soviet Union's collapse and
4814-401: A year). Juvenile correctional facilities are operated by local or state governments and serve as longer-term placements for any minor adjudicated as delinquent and ordered by a judge to be confined. As of January 2023, the United States has the sixth-highest per capita incarceration rate in the world—531 people per 100,000 inhabitants—and the largest prison and jail population in
4980-905: Is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. Fluorescent lamp fixtures are more costly than incandescent lamps, because they require a ballast to regulate the current through the lamp, but the lower energy cost typically offsets the higher initial cost. Compact fluorescent lamps are available in the same popular sizes as incandescent lamps and are used as an energy-saving alternative in homes. Because they contain mercury, many fluorescent lamps are classified as hazardous waste . The United States Environmental Protection Agency recommends that fluorescent lamps be segregated from general waste for recycling or safe disposal, and some jurisdictions require recycling of them. The solid-state light-emitting diode (LED) has been popular as an indicator light in consumer electronics and professional audio gear since
5146-464: Is a federal union of 50 states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the states of Alaska to the northwest and the archipelagic Hawaii in the Pacific Ocean . The United States also asserts sovereignty over five major island territories and various uninhabited islands . The country has
Headlamp - Misplaced Pages Continue
5312-606: Is a legal requirement to adjust the headlamps temporarily so that their wrong-side beam distribution does not dazzle oncoming drivers. This may be achieved by methods including adhering opaque decals or prismatic lenses to a designated part of the lens. Some projector-type headlamps can be made to produce a proper left- or right-traffic beam by shifting a lever or other movable element in or on the lamp assembly. Many tungsten (pre-halogen) European-code headlamps made in France by Cibié, Marchal, and Ducellier could be adjusted to produce either
5478-591: Is believed to be the first widespread culture in the Americas. Over time, indigenous North American cultures grew increasingly sophisticated, and some, such as the Mississippian culture , developed agriculture , architecture , and complex societies . In the post-archaic period , the Mississippian cultures were located in the midwestern , eastern , and southern regions, and the Algonquian in
5644-461: Is bright, and above is dark. On the side of the beam facing away from oncoming traffic (right in right-traffic countries, left in left-traffic countries), this cutoff sweeps or steps upward to direct light to road signs and pedestrians. SAE low beams may or may not have a cutoff, and if a cutoff is present, it may be of two different general types: VOL , which is conceptually similar to the ECE beam in that
5810-498: Is known as the presidential system , in contrast to the parliamentary system , where the executive is part of the legislative body. Many countries around the world imitated this aspect of the 1789 Constitution of the United States , especially in the Americas. The Constitution is silent on political parties. However, they developed independently in the 18th century with the Federalist and Anti-Federalist parties. Since then,
5976-438: Is now the United States experienced conflicts with Native Americans, they also engaged in trade, exchanging European tools for food and animal pelts. Relations ranged from close cooperation to warfare and massacres. The colonial authorities often pursued policies that forced Native Americans to adopt European lifestyles, including conversion to Christianity. Along the eastern seaboard, settlers trafficked African slaves through
6142-465: Is often sealed inside an additional layer of glass. The outer glass is a safety precaution, to reduce ultraviolet emission and to contain hot glass shards should the inner envelope explode during operation. Oily residue from fingerprints may cause a hot quartz envelope to shatter due to excessive heat buildup at the contamination site. The risk of burns or fire is also greater with bare bulbs, leading to their prohibition in some places, unless enclosed by
6308-484: Is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric generators or battery systems. Battery -powered light is often reserved for when and where stationary lights fail, often in the form of flashlights or electric lanterns , as well as in vehicles. Before electric lighting became common in the early 20th century, people used candles , gas lights , oil lamps , and fires . In 1799–1800, Alessandro Volta created
6474-557: Is sufficient for cities to be easily visible at night from the air, and from space. External lighting grew at a rate of 3–6 percent for the later half of the 20th century and is the major source of light pollution that burdens astronomers and others with 80% of the world's population living in areas with night time light pollution. Light pollution has been shown to have a negative effect on some wildlife. Electric lamps can be used as heat sources, for example in incubators , as infrared lamps in fast food restaurants and toys such as
6640-407: Is the deciding factor, such as street lighting. More advanced electronic ballasts may be designed to maintain constant light output over the life of the lamp, may drive the lamp with a square wave to maintain completely flicker-free output, and shut down in the event of certain faults. The most efficient source of electric light is the low-pressure sodium lamp. It produces, for all practical purposes,
6806-552: Is the federal agency charged with addressing most environmental-related issues . The idea of wilderness has shaped the management of public lands since 1964, with the Wilderness Act . The Endangered Species Act of 1973 provides a way to protect threatened and endangered species and their habitats. The United States Fish and Wildlife Service implements and enforces the Act. In 2024, the U.S. ranked 34th among 180 countries in
Headlamp - Misplaced Pages Continue
6972-615: Is used to strike the arc. This requires an electrical circuit called an igniter, which is part of the electrical ballast circuitry. After the arc is struck, the internal resistance of the lamp drops to a low level, and the ballast limits the current to the operating current. Without a ballast, excess current would flow, causing rapid destruction of the lamp. Some lamp types contain a small amount of neon, which permits striking at normal running voltage with no external ignition circuitry. Low-pressure sodium lamps operate this way. The simplest ballasts are just an inductor, and are chosen where cost
7138-415: Is useful for lighting designers , because of its low power consumption, low heat generation, instantaneous on/off control, and in the case of single color LEDs, continuity of color throughout the life of the diode and relatively low cost of manufacture. LED lifetime depends strongly on the temperature of the diode. Operating an LED lamp in conditions that increase the internal temperature can greatly shorten
7304-603: The Allies of World War I , helping to turn the tide against the Central Powers . In 1920, a constitutional amendment granted nationwide women's suffrage . During the 1920s and '30s, radio for mass communication and the invention of early television transformed communications nationwide. The Wall Street Crash of 1929 triggered the Great Depression , which President Franklin D. Roosevelt responded to with
7470-553: The Atlantic slave trade . The original Thirteen Colonies that would later found the United States were administered as possessions of Great Britain , and had local governments with elections open to most white male property owners . The colonial population grew rapidly, eclipsing Native American populations; by the 1770s, the natural increase of the population was such that only a small minority of Americans had been born overseas. The colonies' distance from Britain allowed for
7636-549: The Environmental Performance Index . The country joined the Paris Agreement on climate change in 2016 and has many other environmental commitments. The United States is a federal republic of 50 states and a separate federal capital district, Washington, D.C. It also asserts sovereignty over five unincorporated territories and several uninhabited island possessions . The U.S. is
7802-500: The Federal Bureau of Investigation (FBI) and the U.S. Marshals Service have national jurisdiction and specialized duties, such as protecting civil rights , national security and enforcing U.S. federal courts ' rulings and federal laws. State courts conduct most civil and criminal trials, and federal courts handle designated crimes and appeals of state court decisions . There is no unified "criminal justice system" in
7968-471: The Gordon-Keeble , Jensen CV8 , Triumph Vitesse , and Bentley S3 Continental used such an arrangement as well. In 1968, the newly initiated Federal Motor Vehicle Safety Standard 108 required all vehicles to have either the twin or quad round sealed beam headlamp system and prohibited any decorative or protective element in front of an operating headlamp. Glass-covered headlamps like those used on
8134-720: The Great Lakes , Mississippi River and Gulf of Mexico . British colonization of the East Coast began with the Virginia Colony (1607) and Plymouth Colony (1620). The Mayflower Compact and the Fundamental Orders of Connecticut established precedents for representative self-governance and constitutionalism that would develop throughout the American colonies. While European settlers in what
8300-719: The Great Lakes region and along the Eastern Seaboard , while the Hohokam culture and Ancestral Puebloans inhabited the southwest . Native population estimates of what is now the United States before the arrival of European immigrants range from around 500,000 to nearly 10 million. Christopher Columbus began exploring the Caribbean for Spain in 1492, leading to Spanish-speaking settlements and missions from Puerto Rico and Florida to New Mexico and California . France established its own settlements along
8466-519: The Jaguar E-Type , pre-1968 VW Beetle , 1965 Chrysler and Imperial models, Porsche 356 , Citroën DS , and Ferrari Daytona were no longer permitted, and vehicles had to be equipped with uncovered headlamps for the US market. This made it difficult for vehicles with headlamp configurations designed for good aerodynamic performance to achieve it in their US-market configurations. The FMVSS 108
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#17327867502278632-596: The Midwest . At the same time, about one million French Canadians migrated from Quebec to New England . During the Great Migration , millions of African Americans left the rural South for urban areas in the North. Alaska was purchased from Russia in 1867. The Compromise of 1877 effectively ended Reconstruction and white supremacists took local control of Southern politics . African Americans endured
8798-688: The National Park Service and other agencies. About 28% of the country's land is publicly owned and federally managed, primarily in the Western States . Most of this land is protected , though some is leased for commercial use, and less than one percent is used for military purposes. Environmental issues in the United States include debates on non-renewable resources and nuclear energy , air and water pollution , biodiversity , logging and deforestation , and climate change . The U.S. Environmental Protection Agency (EPA)
8964-596: The New Deal , a series of sweeping programs and public works projects combined with financial reforms and regulations . All were intended to protect against future economic depressions. Initially neutral during World War II , the U.S. began supplying war materiel to the Allies of World War II in March 1941 and entered the war in December after the Empire of Japan 's attack on Pearl Harbor . The U.S. developed
9130-778: The Organization of American States and the United States–Mexico–Canada Free Trade Agreement . In South America, Colombia is traditionally considered to be the closest ally of the United States. The U.S. exercises full international defense authority and responsibility for Micronesia , the Marshall Islands , and Palau through the Compact of Free Association . It has increasingly conducted strategic cooperation with India , but its ties with China have steadily deteriorated. Since 2014,
9296-648: The Pentium microprocessor in accordance with Moore's law , rechargeable lithium-ion batteries , the first gene therapy trial, and cloning either emerged in the U.S. or were improved upon there. The Human Genome Project was formally launched in 1990, while Nasdaq became the first stock market in the United States to trade online in 1998. In the Gulf War of 1991, an American-led international coalition of states expelled an Iraqi invasion force that had occupied neighboring Kuwait . The September 11 attacks on
9462-591: The Spanish–American War . (The Philippines was granted full independence from the U.S. on July 4, 1946, following World War II. Puerto Rico and Guam have remained U.S. territories.) American Samoa was acquired by the United States in 1900 after the Second Samoan Civil War . The U.S. Virgin Islands were purchased from Denmark in 1917. The United States entered World War I alongside
9628-627: The US headlamp regulations were amended to allow replaceable-bulb, nonstandard-shape, architectural headlamps with aerodynamic lenses that could for the first time be made of hard-coated polycarbonate . This allowed the first US-market car since 1939 with replaceable bulb headlamps: the 1984 Lincoln Mark VII . These composite headlamps were sometimes referred to as "Euro" headlamps since aerodynamic headlamps were common in Europe. Though conceptually similar to European headlamps with non-standardized shape and replaceable-bulb construction, these headlamps conform to
9794-548: The United States , incandescent light bulbs including halogen bulbs stopped being sold as of August 1, 2023, because they do not meet minimum lumens per watt performance metrics established by the U.S. Department of Energy . Compact fluorescent bulbs are also banned despite their lumens per watt performance because of their toxic mercury that can be released into the home if broken and widespread problems with proper disposal of mercury-containing bulbs. In its modern form,
9960-578: The acetylene flame light . A number of car manufacturers offered Prest-O-Lite calcium carbide acetylene gas generator cylinder with gas feed pipes for lights as standard equipment for 1904 cars. The first electric headlamps were introduced in 1898 on the Columbia Electric Car from the Electric Vehicle Company of Hartford, Connecticut , and were optional. Two factors limited the widespread use of electric headlamps:
10126-700: The cotton gin made the institution increasingly profitable for Southern elites . This sectional conflict regarding slavery culminated in the American Civil War (1861–1865). Eleven slave states seceded and formed the Confederate States of America , while the other states remained in the Union . War broke out in April 1861 after the Confederates bombarded Fort Sumter . After
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#173278675022710292-523: The end of the Cold War in 1991, the U.S. emerged as the world's sole superpower , wielding significant geopolitical influence globally . The U.S. national government is a presidential constitutional federal republic and liberal democracy with three separate branches : legislative , executive , and judicial . It has a bicameral national legislature composed of the House of Representatives ,
10458-537: The fall of communism and the collapse of the Soviet Union , which marked the end of the Cold War and left the United States as the world's sole superpower . The 1990s saw the longest recorded economic expansion in American history , a dramatic decline in U.S. crime rates , and advances in technology . Throughout this decade, technological innovations such as the World Wide Web , the evolution of
10624-400: The global economy in 2023. It possesses by far the largest amount of wealth of any country and has the highest disposable household income per capita among OECD countries. The U.S. ranks among the world's highest in economic competitiveness , productivity , innovation , human rights , and higher education . Its hard power and cultural influence have a global reach. The U.S. is
10790-540: The voltaic pile , the first electric battery. Current from these batteries could heat copper wire to incandescence. Vasily Vladimirovich Petrov developed the first persistent electric arc in 1802, and English chemist Humphry Davy gave a practical demonstration of an arc light in 1806. It took more than a century of continuous and incremental improvement, including numerous designs, patents, and resulting intellectual property disputes, to get from these early experiments to commercially produced incandescent light bulbs in
10956-813: The 1775 Battles of Lexington and Concord , igniting the American Revolutionary War . At the Second Continental Congress , the colonies appointed George Washington commander-in-chief of the Continental Army , and created a committee that named Thomas Jefferson to draft the Declaration of Independence . Two days after passing the Lee Resolution to create an independent nation the Declaration
11122-437: The 1870s for large building and street lighting until it was superseded in the early 20th century by the incandescent light. Carbon arc lamps operate at high power and produce high intensity white light. They also are a point source of light. They remained in use in limited applications that required these properties, such as movie projectors , stage lighting , and searchlights , until after World War II. A discharge lamp has
11288-514: The 1900s the Phoebus cartel formed in an attempt to reduce the life of electric light bulbs, an example of planned obsolescence . Some types of lamp are also sensitive to switching cycles. Rooms with frequent switching, such as bathrooms, can expect much shorter lamp life than what is printed on the box. Compact fluorescent lamps are particularly sensitive to switching cycles. The total amount of artificial light (especially from street light )
11454-446: The 1920s. In 1840, Warren de la Rue enclosed a platinum coil in a vacuum tube and passed an electric current through it, thus creating one of the world's first electric light bulbs . The design was based on the concept that the high melting point of platinum would allow it to operate at high temperatures and that the evacuated chamber would contain fewer gas molecules to react with the platinum, improving its longevity. Although it
11620-540: The 1965 model year, the Buick Riviera had concealable stacked headlamps. Various Mercedes models sold in America used this arrangement because their home-market replaceable-bulb headlamps were illegal in the US. In the late 1950s and early 1960s, some Lincoln , Buick , and Chrysler cars had the headlamps arranged diagonally with the low-beam lamps outboard and above the high-beam lamps. British cars including
11786-509: The 1966–1967 Dodge Charger . Modern headlamps are electrically operated, positioned in pairs, one or two on each side of the front of a vehicle. A headlamp system is required to produce a low and a high beam, which may be produced by multiple pairs of single-beam lamps or by a pair of dual-beam lamps, or a mix of single-beam and dual-beam lamps. High beams cast most of their light straight ahead, maximizing seeing distance but producing too much glare for safe use when other vehicles are present on
11952-455: The 1970s. In the 2000s, efficacy and output have risen to the point where LEDs are now being used in lighting applications such as car headlights and brake lights, in flashlights and bicycle lights, as well as in decorative applications, such as holiday lighting. Indicator LEDs are known for their extremely long life, up to 100,000 hours, but lighting LEDs are operated much less conservatively, and consequently have shorter lives. LED technology
12118-520: The 2010s, political polarization in the country increased between liberal and conservative factions. This polarization was capitalized upon in the January 2021 Capitol attack , when a mob of insurrectionists entered the U.S. Capitol and sought to prevent the peaceful transfer of power in an attempted self-coup d'état . The United States is the world's third-largest country by total area behind Russia and Canada. The 48 contiguous states and
12284-596: The American West have an alpine climate . The climate is arid in the Southwest, Mediterranean in coastal California , and oceanic in coastal Oregon , Washington , and southern Alaska . Most of Alaska is subarctic or polar . Hawaii , the southern tip of Florida and U.S. territories in the Caribbean and Pacific are tropical . States bordering the Gulf of Mexico are prone to hurricanes, and most of
12450-475: The Declaration of Independence on July 4, 1776. The term "United States" and the initialism "U.S.", used as nouns or as adjectives in English, are common short names for the country. The initialism "USA", a noun, is also common. "United States" and "U.S." are the established terms throughout the U.S. federal government , with prescribed rules. In English, the term "America" rarely refers to topics unrelated to
12616-573: The District of Columbia occupy a combined area of 3,119,885 square miles (8,080,470 km ). The coastal plain of the Atlantic seaboard gives way to inland forests and rolling hills in the Piedmont plateau region. The Appalachian Mountains and the Adirondack massif separate the East Coast from the Great Lakes and the grasslands of the Midwest . The Mississippi River System ,
12782-587: The ECE system claim that the SAE system produces too much glare. Comparative studies have repeatedly shown that there is little or no overall safety advantage to either SAE or ECE beams; the two systems' acceptance and rejection by various countries is based primarily on which system is already in use. In North America, the design, performance, and installation of all motor vehicle lighting devices are regulated by Federal and Canada Motor Vehicle Safety Standard 108 , which incorporates SAE technical standards. Elsewhere in
12948-573: The Elder concluded that major military resources needed to be devoted to North America to win the war against France. For the first time, the continent became one of the main theaters of what could be termed a " world war ". The British colonies' position as an integral part of the British Empire became more apparent during the war, with British military and civilian officials becoming a more significant presence in American life. The war increased
13114-576: The German Ford Taunus P3 and by Cibié for the Citroën Ami 6 . They were prohibited in the United States where round lamps were required until 1975. Another early headlamp styling concept involved conventional round lamps faired into the car's bodywork with aerodynamic glass covers, such as those on the 1961 Jaguar E-Type , and on pre-1967 VW Beetles . Headlight design in the U.S. changed very little from 1940 to 1983. In 1940,
13280-683: The January 1863 Emancipation Proclamation , many freed slaves joined the Union army . The war began to turn in the Union's favor following the 1863 Siege of Vicksburg and Battle of Gettysburg , and the Confederacy surrendered in 1865 after the Union's victory in the Battle of Appomattox Court House . The Reconstruction era followed the war. After the assassination of President Abraham Lincoln , Reconstruction Amendments were passed to protect
13446-541: The Kenner Easy-Bake Oven . Lamps can also be used for light therapy to deal with such issues as vitamin D deficiency , skin conditions such as acne and dermatitis , skin cancers , and seasonal affective disorder . Lamps which emit a specific frequency of blue light are also used to treat neonatal jaundice with the treatment which was initially undertaken in hospitals being able to be conducted at home. Electric lamps can also be used as
13612-902: The Netherlands in 1976 concluded that yellow and white headlamps are equivalent as regards traffic safety, though yellow light causes less discomfort glare than white light. Researchers note that tungsten filament lamps emit only a small amount of the blue light blocked by a selective-yellow filter, so such filtration makes only a small difference in the characteristics of the light output, and suggest that headlamps using newer kinds of sources such as metal halide (HID) bulbs may, through filtration, give off less visually distracting light while still having greater light output than halogen ones. Selective yellow headlamps are no longer common, but are permitted in various countries throughout Europe as well as in non-European locales such as South Korea, Japan and New Zealand. In Iceland , yellow headlamps are allowed and
13778-611: The Rocky Mountains, the Yellowstone Caldera , is the continent's largest volcanic feature. In 2021, the United States had 8% of global permanent meadows and pastures and 10% of cropland. With its large size and geographic variety, the United States includes most climate types. East of the 100th meridian , the climate ranges from humid continental in the north to humid subtropical in the south. The western Great Plains are semi-arid . Many mountainous areas of
13944-647: The U.S. has become a key ally of Ukraine ; it has also provided the country with significant military equipment and other support in response to Russia's 2022 invasion . The president is the commander-in-chief of the United States Armed Forces and appoints its leaders, the secretary of defense and the Joint Chiefs of Staff . The Department of Defense , which is headquartered at the Pentagon near Washington, D.C., administers five of
14110-661: The U.S. territories." Despite disparate systems of confinement, four main institutions dominate: federal prisons , state prisons , local jails, and juvenile correctional facilities . Federal prisons are run by the Federal Bureau of Prisons and hold people who have been convicted of federal crimes, including pretrial detainees. State prisons, run by the official department of correction of each state, hold sentenced people serving prison time (usually longer than one year) for felony offenses. Local jails are county or municipal facilities that incarcerate defendants prior to trial; they also hold those serving short sentences (typically under
14276-533: The UK and Thomas Edison in the US independently developing functional incandescent lamps. Swan's bulbs, based on designs by William Staite, were successful, but the filaments were too thick. Edison worked to create bulbs with thinner filaments, leading to a better design. The rivalry between Swan and Edison eventually led to a merger, forming the Edison and Swan Electric Light Company . By the early twentieth century these had completely replaced arc lamps . The turn of
14442-527: The US National Highway Traffic Safety Administration states that nearly half of all traffic-related fatalities occur in the dark, despite only 25% of traffic travelling during darkness. Other vehicles, such as trains and aircraft, are required to have headlamps. Bicycle headlamps are often used on bicycles, and are required in some jurisdictions. They can be powered by a battery or a small generator like
14608-674: The US, SAE standard headlamps are aimed without regard to headlamp mounting height. This gives vehicles with high-mounted headlamps a seeing distance advantage, at the cost of increased glare to drivers in lower vehicles. By contrast, ECE headlamp aim angle is linked to headlamp mounting height, to give all vehicles roughly equal seeing distance and all drivers roughly equal glare. Headlamps are generally required to produce white light, according to both ECE and SAE standards. ECE Regulation 48 currently requires new vehicles to be equipped with headlamps emitting white light. Different headlamp technologies produce different characteristic types of white light;
14774-464: The United States and the peaceful transfer of power , respectively. The Louisiana Purchase of 1803 from France nearly doubled the territory of the United States. Lingering issues with Britain remained , leading to the War of 1812 , which was fought to a draw. Spain ceded Florida and its Gulf Coast territory in 1819. In the late 18th century, American settlers began to expand westward , many with
14940-714: The United States entered the Cold War, where geopolitical tensions between the U.S. and the Soviet Union led the two countries to dominate world affairs . The U.S. utilized the policy of containment to limit the USSR's sphere of influence, and prevailed in the Space Race , which culminated with the first crewed Moon landing in 1969. Domestically, the U.S. experienced economic growth , urbanization , and population growth following World War II . The civil rights movement emerged, with Martin Luther King Jr. becoming
15106-666: The United States has operated as a de facto two-party system , though the parties in that system have been different at different times. The two main national parties are presently the Democratic and the Republican . The former is perceived as relatively liberal in its political platform while the latter is perceived as relatively conservative . In the American federal system , sovereign powers are shared between two levels of elected government: national and state. People in
15272-593: The United States in 2001 by the pan-Islamist militant organization al-Qaeda led to the war on terror , and subsequent military interventions in Afghanistan and Iraq . The cultural impact of the attacks was profound and long-lasting. The U.S. housing bubble culminated in 2007 with the Great Recession , the largest economic contraction since the Great Depression. Coming to a head in
15438-597: The United States of America to Spain" to seek assistance in the Revolutionary War effort. The first known public usage is an anonymous essay published in the Williamsburg newspaper, The Virginia Gazette , on April 6, 1776. By June 1776, the "United States of America" appeared in the Articles of Confederation and the Declaration of Independence . The Second Continental Congress adopted
15604-593: The United States, despite the usage of "the Americas " as the totality of North and South America. "The States" is an established colloquial shortening of the name, used particularly from abroad; "stateside" is the corresponding adjective or adverb. The first inhabitants of North America migrated from Siberia across the Bering land bridge about 12,000 years ago; the Clovis culture , which appeared around 11,000 BC,
15770-624: The United States, except Iran , North Korea , and Bhutan . Though Taiwan does not have formal diplomatic relations with the U.S., it maintains close unofficial relations. The United States regularly supplies Taiwan with military equipment to deter potential Chinese aggression. Its geopolitical attention also turned to the Indo-Pacific when the United States joined the Quadrilateral Security Dialogue with Australia, India, and Japan. The United States has
15936-509: The United States. The American prison system is largely heterogenous, with thousands of relatively independent systems operating across federal, state, local, and tribal levels. In 2023, "these systems [held] almost 2 million people in 1,566 state prisons, 98 federal prisons, 3,116 local jails, 1,323 juvenile correctional facilities, 181 immigration detention facilities, and 80 Indian country jails, as well as in military prisons , civil commitment centers, state psychiatric hospitals, and prisons in
16102-454: The United States. This headlamp format was not widely accepted in continental Europe, which found replaceable bulbs and variations in the size and shape of headlamps useful in car design. Technology moved forward in the rest of the world. In 1962 a European consortium of bulb- and headlamp-makers introduced the first halogen lamp for vehicle headlamp use, the H1 . Shortly thereafter headlamps using
16268-399: The amount of glare permitted toward other drivers on low beam (SAE permits much more glare), the minimum amount of light required to be thrown straight down the road (SAE requires more), and the specific locations within the beam at which minimum and maximum light levels are specified. ECE low beams are characterized by a distinct horizontal "cutoff" line at the top of the beam. Below the line
16434-628: The appearance of an illuminated lightbulb above a person's head — signifies sudden inspiration. In the Middle East , a light bulb symbol has a sexual connotation. A stylized depiction of a light bulb features as the logo of the Turkish AK Party . United States The United States of America ( USA ), commonly known as the United States ( U.S. ) or America , is a country primarily located in North America . It
16600-522: The car until 1978, when the limit was raised to 75,000. An increase in high-beam intensity to take advantage of the higher allowance could not be achieved without a move to halogen technology, and so sealed- beam headlamps with internal halogen lamps became available for use on 1979 models in the United States. As of 2010 halogen sealed beams dominate the sealed-beam market, which has declined steeply since replaceable- bulb headlamps were permitted in 1983. High-intensity discharge (HID) systems appeared in
16766-416: The car's styling. When the lamps are switched on, the covers are swung out of the way, usually downward or upward, for example on the 1992 Jaguar XJ220 . The door mechanism may be actuated by vacuum pots, as on some Ford vehicles of the late 1960s through early 1980s such as the 1967–1970 Mercury Cougar , or by an electric motor as on various Chrysler products of the middle 1960s through late 1970s such as
16932-416: The carbon rods are short-lived and require constant adjustment in use, as the intense heat of the arc erodes them. The lamps produce significant ultraviolet output, they require ventilation when used indoors, and due to their intensity they need protection from direct sight. Invented by Humphry Davy around 1805, the carbon arc was the first practical electric light. It was used commercially beginning in
17098-428: The century saw further improvements in bulb longevity and efficiency, notably with the introduction of the tungsten filament by William D. Coolidge , who applied for a patent in 1912. This innovation became a standard for incandescent bulbs for many years. In 1910, Georges Claude introduced the first neon light, paving the way for neon signs which would become ubiquitous in advertising. In 1934, Arthur Compton ,
17264-457: The contiguous United States are in the State of California, about 84 miles (135 km) apart. At an elevation of 20,310 feet (6,190.5 m), Alaska's Denali is the highest peak in the country and continent. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands , and Hawaii consists of volcanic islands. The supervolcano underlying Yellowstone National Park in
17430-433: The conventional two-filament type, and the intermediate beam combined low beam on the driver's side with high beam on the passenger's side, so as to maximise the view of the roadside while minimizing glare toward oncoming traffic. The last vehicles with a foot-operated dimmer switch were the 1991 Ford F-Series and E-Series [Econoline] vans. Fog lamps were new for 1938 Cadillacs, and their 1952 "Autronic Eye" system automated
17596-437: The correct traffic-handedness. North American vehicle owners sometimes privately import and install Japanese-market (JDM) headlamps on their car in the mistaken belief that the beam performance will be better, when in fact such misapplication is quite hazardous and illegal. Vehicle headlamps have been found unable to illuminate an assured clear distance ahead at speeds above 60 km/h (40 mph). It may be unsafe and, in
17762-556: The country's GDP. The U.S. has 42% of the world's nuclear weapons —the second-largest share after Russia. The United States has the third-largest combined armed forces in the world, behind the Chinese People's Liberation Army and Indian Armed Forces . The military operates about 800 bases and facilities abroad, and maintains deployments greater than 100 active duty personnel in 25 foreign countries. State defense forces (SDFs) are military units that operate under
17928-469: The country's territory would expand with the admission of new states , rather than the expansion of existing states. The U.S. Constitution was drafted at the 1787 Constitutional Convention to overcome the limitations of the Articles. It went into effect in 1789, creating a federal republic governed by three separate branches that together ensured a system of checks and balances . George Washington
18094-458: The cutoff is located at the top of the left side of the beam and aimed slightly below horizontal, or VOR , which has the cutoff at the top of the right side of the beam and aimed at the horizon. Proponents of each headlamp system decry the other as inadequate and unsafe: US proponents of the SAE system claim that the ECE low beam cutoff gives short seeing distances and inadequate illumination for overhead road signs, while international proponents of
18260-713: The development of self-governance, and the First Great Awakening , a series of Christian revivals , fueled colonial interest in religious liberty . For a century, the American colonists had been providing their own troops and materiel in conflicts with indigenous peoples allied with Britain's colonial rivals , especially France, and the Americans had begun to develop a sense of self-defense and self-reliance separate from Britain. The French and Indian War (1754–1763) took on new significance for all North American colonists after Parliament under William Pitt
18426-414: The dispossession of native inhabitants . As more states were admitted , a North–South division over slavery led to the secession of the Confederate States of America , which fought states remaining in the Union in the 1861–1865 American Civil War . With the victory and preservation of the United States, slavery was abolished nationally . By 1900, the country had established itself as a great power ,
18592-452: The early 1990s, first in the BMW 7 Series . 1996's Lincoln Mark VIII was an early American effort at HIDs, and was the only car with DC HIDs. Beyond the engineering, performance, and regulatory-compliance aspects of headlamps, there is the consideration of the various ways they are designed and arranged on a motor vehicle. Headlamps were round for many years because that is the native shape of
18758-577: The energy consumed is emitted as visible, usable light . The remaining 95% is lost as heat . In warmer climates, the emitted heat must then be removed, putting additional pressure on ventilation or air conditioning systems. In colder weather, the heat byproduct has some value, and has been successfully harnessed for warming in devices such as heat lamps . Incandescent bulbs are nonetheless being phased out in favor of technologies like CFLs and LED bulbs in many countries due to their low energy efficiency. The European Commission estimated in 2012 that
18924-580: The environment for labor unions to begin to flourish . This period eventually ended with the advent of the Progressive Era , which was characterized by significant reforms. Pro-American elements in Hawaii overthrew the Hawaiian monarchy ; the islands were annexed in 1898. That same year, Puerto Rico , the Philippines , and Guam were ceded to the U.S. by Spain after the latter's defeat in
19090-417: The existing 7-inch round format, or a system of four 165 by 100 mm (6.5 by 3.9 in) units, two high/low and two high-beam. corresponding to the existing 5 + 3 ⁄ 4 in (146 mm) round format. The rectangular headlamp design became so prevalent in U.S.-made cars that only a few models continued using round headlamps by 1979. In 1983, granting a 1981 petition from Ford Motor Company,
19256-541: The federal government often applied policies of Indian removal or assimilation . The Trail of Tears (1830–1850) was a U.S. government policy that forcibly removed and displaced most Native Americans living east of the Mississippi River to lands far to the west. These and earlier organized displacements prompted a long series of American Indian Wars west of the Mississippi. The Republic of Texas
19422-606: The first nuclear weapons and used them against the Japanese cities of Hiroshima and Nagasaki in August 1945, ending the war. The United States was one of the " Four Policemen " who met to plan the post-war world , alongside the United Kingdom , Soviet Union , and China . The U.S. emerged relatively unscathed from the war, with even greater economic power and international political influence . After World War II,
19588-665: The first settlement of the Thirteen Colonies in Virginia in 1607. Clashes with the British Crown over taxation and political representation sparked the American Revolution , with the Second Continental Congress formally declaring independence on July 4, 1776. Following its victory in the 1775–1783 Revolutionary War , the country continued to expand westward across North America , resulting in
19754-650: The front turn signals , or by special daytime running lamps. Functionally dedicated daytime running lamps not involving the headlamps are required on all new cars first sold in the European Union since February 2011. In addition to the EU and Canada, countries requiring DRL include Albania, Argentina, Bosnia and Herzegovina, Czech republic, Colombia (no more from Aug/2011), Iceland, Israel, Macedonia, Norway, Moldova, Russia, Serbia, and Uruguay. There are two different beam pattern and headlamp construction standards in use in
19920-476: The front fenders, which were smooth until the lights were cranked out—each with its own small dash-mounted crank—by the operator. They aided aerodynamics when the headlamps were not in use and were among the Cord's signature design features. Later hidden headlamps require one or more vacuum-operated servos and reservoirs, with associated plumbing and linkage, or electric motors , geartrains and linkages to raise
20086-476: The headlamp design, construction, and performance specifications of US Federal Motor Vehicle Safety Standard 108 rather than the internationalized European safety standards used outside North America. Nevertheless, this change to US regulations made it possible for headlamp styling in the US market to move closer to that in Europe. Hidden headlamps were introduced in 1936, on the Cord 810/812 . They were mounted in
20252-437: The incandescent light bulb consists of a coiled filament of tungsten sealed in a globular glass chamber, either a vacuum or full of an inert gas such as argon . When an electric current is connected, the tungsten is heated to 2,000 to 3,300 K (1,730 to 3,030 °C; 3,140 to 5,480 °F) and glows, emitting light that approximates a continuous spectrum . Incandescent bulbs are highly inefficient, in that just 2–5% of
20418-463: The integration of Army National Guard units and personnel into the U.S. Army and (since 1947) the U.S. Air Force. There are about 18,000 U.S. police agencies from local to national level in the United States. Law in the United States is mainly enforced by local police departments and sheriff departments in their municipal or county jurisdictions. The state police departments have authority in their respective state , and federal agencies such as
20584-443: The lamp in the socket of a light fixture , which is often called a "lamp" as well. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet mount . The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current , gas-discharge lamps , which produce light by means of an electric arc through
20750-429: The lamp's life. Some lasers have been adapted as an alternative to LEDs to provide highly focused illumination. Carbon arc lamps consist of two carbon rod electrodes in open air, supplied by a current-limiting ballast . The electric arc is struck by touching the rod tips then separating them. The ensuing arc produces a white-hot plasma between the rod tips. These lamps have higher efficacy than filament lamps, but
20916-574: The lamps to an exact position to assure correct aiming despite ice, snow, and age. Some hidden headlamp designs, such as those on the Saab Sonett III, used a lever-operated mechanical linkage to raise the headlamps into position. During the 1960s and 1970s, many notable sports cars used this feature such as the Chevrolet Corvette (C3) , Ferrari Berlinetta Boxer and Lamborghini Countach as they allowed low bonnet lines but raised
21082-452: The lights to the required height, but since 2004 no modern volume-produced car models use hidden headlamps because they present difficulties in complying with pedestrian-protection provisions added to international auto safety regulations regarding protuberances on car bodies to minimize injury to pedestrians struck by cars. Some hidden headlamps themselves do not move, but rather are covered when not in use by panels designed to blend in with
21248-496: The low beams in their conventional outboard location, and the high beams vertically stacked at the centerline of the car, but no such designs reached volume production. An example arrangement includes the stacking of two headlamps on each side, with low beams above high beams. The Nash Ambassador used this arrangement in the 1957 model year. Pontiac used this design starting in the 1963 model year; American Motors , Ford , Cadillac , and Chrysler followed two years later. Also in
21414-406: The luminaire. Those designed for 12- or 24-volt operation have compact filaments, useful for good optical control. Also, they have higher efficacies (lumens per watt) and longer lives than non-halogen types. The light output remains almost constant throughout their life. Fluorescent lamps consist of a glass tube that contains mercury vapour or argon under low pressure. Electricity flowing through
21580-482: The military draft (leading to the end of conscription in 1973) and wide opposition to U.S. intervention in Vietnam (with the U.S. totally withdrawing in 1975). A societal shift in the roles of women was significantly responsible for the large increase in female paid labor participation during the 1970s, and by 1985 the majority of American women aged 16 and older were employed. The late 1980s and early 1990s saw
21746-424: The modern vehicle electrical system. The Guide Lamp Company introduced "dipping" (low-beam) headlamps in 1915, but the 1917 Cadillac system allowed the light to be dipped using a lever inside the car rather than requiring the driver to stop and get out. The 1924 Bilux bulb was the first modern unit, having the light for both low (dipped) and high (main) beams of a headlamp emitting from a single bulb. A similar design
21912-612: The most attractive to the population are the most vulnerable. The U.S. is one of 17 megadiverse countries containing large numbers of endemic species : about 17,000 species of vascular plants occur in the contiguous United States and Alaska, and over 1,800 species of flowering plants are found in Hawaii, few of which occur on the mainland. The United States is home to 428 mammal species, 784 birds, 311 reptiles, 295 amphibians , and around 91,000 insect species. There are 63 national parks , and hundreds of other federally managed parks, forests, and wilderness areas , managed by
22078-662: The most violent, the California genocide of thousands of Native inhabitants, lasted into the early 1870s, just as additional western territories and states were created. During the colonial period, slavery had been legal in the American colonies , though the practice began to be significantly questioned during the American Revolution. States in the North enacted abolition laws , though support for slavery strengthened in Southern states , as inventions such as
22244-450: The new light source were introduced in Europe. These were effectively prohibited in the US, where standard-size sealed beam headlamps were mandatory and intensity regulations were low. US lawmakers faced pressure to act, due both to lighting effectiveness and to vehicle aerodynamics/fuel savings. High-beam peak intensity, capped at 140,000 candela per side of the car in Europe, was limited in the United States to 37,500 candela on each side of
22410-437: The new system. Separate low and high beam lamps eliminated the need for compromise in lens design and filament positioning required in a single unit. Other cars followed suit when all states permitted the new lamps by the time the 1958 models were brought to market. The four-lamp system permitted more design flexibility and improved low and high beam performance. Auto stylists such as Virgil Exner carried out design studies with
22576-410: The number of hours of operation at which 50% of them fail, that is the median life of the lamps. Production tolerances as low as 1% can create a variance of 25% in lamp life, so in general some lamps will fail well before the rated life expectancy, and some will last much longer. For LEDs, lamp life is defined as the operation time at which 50% of lamps have experienced a 70% decrease in light output. In
22742-408: The policy of redlining later adopted by the federal Home Owners' Loan Corporation . An explosion of technological advancement accompanied by the exploitation of cheap immigrant labor led to rapid economic expansion during the late 19th and early 20th centuries , allowing the United States to outpace the economies of England, France, and Germany combined. This fostered the amassing of power by
22908-574: The primary colonial grievances was a denial of their rights as Englishmen , particularly the right to representation in the British government that taxed them . To demonstrate their dissatisfaction and resolve, the First Continental Congress met in 1774 and passed the Continental Association , a colonial boycott of British goods that proved effective. The British attempt to then disarm the colonists resulted in
23074-515: The rights of African Americans . National infrastructure, including transcontinental telegraph and railroads , spurred growth in the American frontier . From 1865 through 1917 an unprecedented stream of immigrants arrived in the United States, including 24.4 million from Europe. Most came through the port of New York City , and New York City and other large cities on the East Coast became home to large Jewish , Irish , and Italian populations, while many Germans and Central Europeans moved to
23240-407: The road, as the glare they produce will dazzle other drivers. International ECE Regulations permit higher-intensity high-beam headlamps than are allowed under North American regulations . Most low-beam headlamps are specifically designed for use on only one side of the road . Headlamps for use in left-traffic countries have low-beam headlamps that "dip to the left"; the light is distributed with
23406-495: The road. Because there is no special control of upward light, high beams also cause backdazzle from fog , rain and snow due to the retroreflection of the water droplets . Low beams have stricter control of upward light, and direct most of their light downward and either rightward (in right-traffic countries) or leftward (in left-traffic countries), to provide forward visibility without excessive glare or backdazzle. Low beam (dipped beam, passing beam, meeting beam) headlamps provide
23572-614: The rocky Great Basin and Chihuahua , Sonoran , and Mojave deserts. In the northwest corner of Arizona , carved by the Colorado River over millions of years, is the Grand Canyon , a steep-sided canyon and popular tourist destination known for its overwhelming visual size and intricate, colorful landscape. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast . The lowest and highest points in
23738-475: The selection of high and low beams. Directional lighting, using a switch and electromagnetically shifted reflector to illuminate the curbside only, was introduced in the rare, one-year-only 1935 Tatra . Steering-linked lighting was featured on the 1947 Tucker Torpedo's center-mounted headlight and was later popularized by the Citroën DS . This made it possible to turn the light in the direction of travel when
23904-585: The short life of filaments in the harsh automotive environment, and the difficulty of producing dynamos small enough, yet powerful enough to produce sufficient current. Peerless made electric headlamps standard in 1908. A Birmingham, England firm called Pockley Automobile Electric Lighting Syndicate marketed the world's first electric car-lights as a complete set in 1908, which consisted of headlamps, sidelamps, and tail lights that were powered by an eight-volt battery. In 1912 Cadillac integrated their vehicle's Delco electrical ignition and lighting system, forming
24070-573: The six service branches, which are made up of the U.S. Army , Marine Corps , Navy , Air Force , and Space Force . The Coast Guard is administered by the Department of Homeland Security in peacetime and can be transferred to the Department of the Navy in wartime. The United States spent $ 916 billion on its military in 2023, which is by far the largest amount of any country , making up 37% of global military spending and accounting for 3.4% of
24236-545: The sole authority of a state government. SDFs are authorized by state and federal law but are under the command of the state's governor . They are distinct from the state's National Guard units in that they cannot become federalized entities. A state's National Guard personnel, however, may be federalized under the National Defense Act Amendments of 1933 , which created the Guard and provides for
24402-543: The states are also represented by local elected governments , which are administrative divisions of the states. States are subdivided into counties or county equivalents , and further divided into municipalities . The District of Columbia is a federal district containing the U.S. capital, Washington, D.C. . The federal district is an administrative division of the federal government. Federally recognized tribes govern 326 Indian reservations . The United States has an established structure of foreign relations, and it has
24568-630: The steering wheel turned. The standardized 7-inch (178 mm) round sealed-beam headlamp, one per side, was required for all vehicles sold in the United States from 1940, virtually freezing usable lighting technology in place until the 1970s for Americans. In 1957 the law changed to allow smaller 5.75-inch (146 mm) round sealed beams, two per side of the vehicle, and in 1974 rectangular sealed beams were permitted as well. Britain, Australia, and some other Commonwealth countries, as well as Japan and Sweden , also made extensive use of 7-inch sealed beams, though they were not mandated as they were in
24734-510: The structure and responsibilities of the national federal government and its relationship with the individual states. The U.S. Constitution is the world's oldest national constitution still in effect (from March 4, 1789). Composed of three branches, all headquartered in Washington, D.C., the federal government is the national government of the United States. It is regulated by a strong system of checks and balances . The three-branch system
24900-419: The tube causes the gases to give off ultraviolet energy. The inside of the tubes are coated with phosphors that give off visible light when struck by ultraviolet photons . They have much higher efficiency than incandescent lamps. For the same amount of light generated, they typically use around one-quarter to one-third the power of an incandescent. The typical luminous efficacy of fluorescent lighting systems
25066-491: The vehicle regulations in Monaco still officially require selective yellow light from all vehicles' low beam and high beam headlamps, and fog lamps if present. Lamp (electrical component) An electric light , lamp , or light bulb is an electrical component that produces light . It is the most common form of artificial lighting . Lamps usually have a base made of ceramic , metal, glass, or plastic which secures
25232-461: The white specification is quite large and permits a wide range of apparent colour from warm white (with a brown-orange-amber-yellow cast) to cold white (with a blue-violet cast). Previous ECE regulations also permitted selective yellow light. A research experiment done in the UK in 1968 using tungsten (non-halogen) lamps found that visual acuity is about 3% better with selective yellow headlamps than with white ones of equal intensity. Research done in
25398-582: The world's fourth-longest river system , runs predominantly north–south through the heart of the country. The flat and fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast. The Rocky Mountains , west of the Great Plains, extend north to south across the country, peaking at over 14,000 feet (4,300 m) in Colorado . Farther west are
25564-583: The world's second-largest diplomatic corps as of 2024 . It is a permanent member of the United Nations Security Council , and home to the United Nations headquarters . The United States is a member of the G7 , G20 , and OECD intergovernmental organizations. Almost all countries have embassies and many have consulates (official representatives) in the country. Likewise, nearly all countries host formal diplomatic missions with
25730-461: The world's third-largest land area , largest exclusive economic zone , and third-largest population , exceeding 334 million. Its three largest metropolitan areas are New York , Los Angeles , and Chicago , and its three most populous states are California , Texas , and Florida . Paleo-Indians migrated across the Bering land bridge more than 12,000 years ago, and formed various civilizations and societies . British colonization led to
25896-444: The world's oldest surviving federation, and its presidential system of national government has been adopted, in whole or in part, by many newly independent states worldwide following their decolonization . It is a liberal representative democracy "in which majority rule is tempered by minority rights protected by law ". The Constitution of the United States serves as the country's supreme legal document , also establishing
26062-553: The world's tornadoes occur in the country , mainly in Tornado Alley . Overall, the United States receives more high-impact extreme weather incidents than any other country. Extreme weather became more frequent in the U.S. in the 21st century, with three times the number of reported heat waves as in the 1960s. In the American Southwest , droughts became more persistent and more severe. The regions considered as
26228-563: The world, ECE internationalized regulations are in force either by reference or by incorporation in individual countries' vehicular codes. US laws required sealed beam headlamps on all vehicles between 1940 and 1983, and other countries such as Japan, United Kingdom, and Australia also made extensive use of sealed beams. In most other countries, and in the US since 1984, replaceable-bulb headlamps predominate. Headlamps must be kept in proper aim. Regulations for aim vary from country to country and from beam specification to beam specification. In
26394-470: The world: The ECE standard, which is allowed or required in virtually all industrialized countries except the United States, and the SAE standard that is mandatory only in the US. Japan formerly had bespoke lighting regulations similar to the US standards, but for the left side of the road. However, Japan now adheres to the ECE standard. The differences between the SAE and ECE headlamp standards are primarily in
26560-575: Was annexed in 1845, and the 1846 Oregon Treaty led to U.S. control of the present-day American Northwest . Victory in the Mexican–American War resulted in the 1848 Mexican Cession of California, Nevada, Utah, and much of present-day Colorado and the American Southwest . The California gold rush of 1848–1849 spurred a huge migration of white settlers to the Pacific coast, leading to even more confrontations with Native populations. One of
26726-759: Was adopted on July 4, 1776. The political values of the American Revolution included liberty , inalienable individual rights ; and the sovereignty of the people ; supporting republicanism and rejecting monarchy , aristocracy , and all hereditary political power; civic virtue ; and vilification of political corruption . The Founding Fathers of the United States , who included Washington, Jefferson, John Adams , Benjamin Franklin , Alexander Hamilton , John Jay , James Madison , Thomas Paine , and many others, were inspired by Greco-Roman , Renaissance , and Enlightenment philosophies and ideas. The Articles of Confederation were ratified in 1781 and established
26892-415: Was amended in 1974 to permit rectangular sealed-beam headlamps. This allowed manufacturers flexibility to lower the hoods on new cars. These could be placed in horizontal arrays or in vertically stacked pairs. As previously with round lamps, the US permitted only two standardized sizes of rectangular sealed-beam lamp: A system of two 200 by 142 mm (7.9 by 5.6 in) high/low beam units corresponding to
27058-434: Was an efficient design, the cost of the platinum made it impractical for commercial use. William Greener , an English inventor, made significant contributions to early electric lighting with his lamp in 1846 (patent specification 11076), laying the groundwork for future innovations such as those by Thomas Edison. The late 1870s and 1880s were marked by intense competition and innovation, with inventors like Joseph Swan in
27224-583: Was elected the country's first president under the Constitution, and the Bill of Rights was adopted in 1791 to allay skeptics' concerns about the power of the more centralized government. His resignation as commander-in-chief after the Revolutionary War and his later refusal to run for a third term as the country's first president established a precedent for the supremacy of civil authority in
27390-436: Was introduced in 1925 by Guide Lamp called the "Duplo". In 1927 the foot-operated dimmer switch or dip switch was introduced and became standard for much of the century. 1933–1934 Packards featured tri-beam headlamps, the bulbs having three filaments. From highest to lowest, the beams were called "country passing", "country driving" and "city driving". The 1934 Nash also used a three-beam system, although in this case with bulbs of
27556-433: Was not a trivial exercise; as noted by Arthur A. Bright, "A great deal of experimentation had to be done on lamp sizes and shapes, cathode construction, gas pressures of both argon and mercury vapor, colors of fluorescent powders, methods of attaching them to the inside of the tube, and other details of the lamp and its auxiliaries before the new device was ready for the public." The first practical LED arrived in 1962. In
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