Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz).

The primary properties of visible light are intensity, propagation-direction, frequency or wavelength spectrum and polarization. Its speed in a vacuum, 299 792 458 metres a second (m/s), is one of the fundamental constants of nature, as with all types of electromagnetic radiation (EMR), light is found in experimental conditions to always move at this speed in a vacuum.In physics, the term 'light' sometimes refers to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. Like all types of electromagnetic radiation, visible light propagates as waves. However, the energy imparted by the waves is absorbed at single locations the way particles are absorbed. The absorbed energy of the electromagnetic waves is called a photon and represents the quanta of light. When a wave of light is transformed and absorbed as a photon, the energy of the wave instantly collapses to a single location and this location is where the photon "arrives".

Light

The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, 326 Indian reservations, and some minor possessions. At 3.8 million square miles (9.8 million square kilometers), it is the world's third- or fourth-largest country by total area. It borders Canada to the north and Mexico to the south. With a population of more than 331 million people, it is the third most populous country in the world. The national capital is Washington, D.C., and the most populous city is New York City.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago, and European colonization began in the 16th century. The United States emerged from the thirteen British colonies established along the East Coast. Disputes over taxation and political representation with Great Britain led to the American Revolutionary War (1775–1783), which established independence. In the late 18th century, the U.S. began expanding across North America, gradually obtaining new territories, sometimes through war, frequently displacing Native Americans, and admitting new states; by 1848, the United States spanned the continent.

United States

United_States

A library is a collection of materials, books or media that are easily accessible for use and not just for display purposes. It is responsible for housing updated information in order to meet the user's needs on a daily basis. A Library provides physical (hard copies documents) or digital access (soft copies) materials, and may be a physical location or a virtual space, or both. A library's collection can include printed materials and other physical resources in many formats such as DVDs, CDs and Cassette as well as access to information, music or other content held on bibliographic databases.
A library, which may vary widely in size, may be organized for use and maintained by a public body such as a government, an institution/ schools, a corporation, or a private individual. In addition to providing materials, libraries also provide the services of librarians who are trained and experts at finding, selecting, circulating and organizing information and at interpreting information needs, navigating and analyzing very large amounts of information with a variety of resources. Hence, librarians go an extra mile to meet the user's need by ensuring that their users are satisfied with the information provided. A Librarian is one person who is expected to be very vibrant and innovative especially in this digital world.Library buildings often provide quiet and conducive areas for studying, as well as common areas for group study and collaboration, and may provide public facilities for access to their electronic resources for instance Computers and Desktop and access to the Internet. The library's clientele and therefore the services offered vary depending on its type: users of a public library have different needs from those of a special library, for example. Libraries may also be community hubs, where programs are delivered and people engage in lifelong learning.

Library

Plants are mainly multicellular organisms, predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, plants were treated as one of two kingdoms including all living things that were not animals, and all algae and fungi were treated as plants. However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). By one definition, plants form the clade Viridiplantae (Latin name for "green plants"), a group that includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, mosses, and the green algae, but excludes the red and brown algae.
Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize, but still have flowers, fruits, and seeds. Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is also common.
There are about 320,000 species of plants, of which the great majority, some 260–290 thousand, produce seeds. Green plants provide a substantial proportion of the world's molecular oxygen, and are the basis of most of Earth's ecosystems.

Plant

A Christmas tree is a decorated tree, usually an evergreen conifer, such as a spruce, pine, or fir, or an artificial tree of similar appearance, associated with the celebration of Christmas, originating in Germany associated with Saint Boniface. The custom was developed in medieval Livonia (present-day Estonia and Latvia), and in early modern Germany where German Protestant Christians brought decorated trees into their homes. It acquired popularity beyond the Lutheran areas of Germany and the Baltic governorates during the second half of the 19th century, at first among the upper classes.The tree was traditionally decorated with "roses made of colored paper, apples, wafers, tinsel, [and] sweetmeats". Moravian Christians began to illuminate Christmas trees with candles, which were ultimately replaced by Christmas lights after the advent of electrification. Today, there is a wide variety of traditional and modern ornaments, such as garlands, baubles, tinsel, and candy canes. An angel or star might be placed at the top of the tree to represent the Angel Gabriel or the Star of Bethlehem, respectively, from the Nativity. Edible items such as gingerbread, chocolate, and other sweets are also popular and are tied to or hung from the tree's branches with ribbons. The Catholic Church had long resisted this custom of the Lutheran Church and the Vatican Christmas tree stood for the first time in Vatican City in 1982.In the Western Christian tradition, Christmas trees are variously erected on days such as the first day of Advent or even as late as Christmas Eve depending on the country; customs of the same faith hold that the two traditional days when Christmas decorations, such as the Christmas tree, are removed are Twelfth Night and, if they are not taken down on that day, Candlemas, the latter of which ends the Christmas-Epiphany season in some denominations.The Christmas tree is sometimes compared with the "Yule-tree", especially in discussions of its folkloric origins.


== History ==


=== Origin of the modern Christmas tree ===

Modern Christmas trees originated during the Renaissance in early modern Germany. Its 16th-century origins are sometimes associated with Protestant Christian reformer Martin Luther, who is said to have first added lighted candles to an evergreen tree.The earliest known firmly dated representation of a Christmas tree is on the keystone sculpture of a private home in Turckheim, Alsace (then part of Germany, today France), with the date 1576.

Christmas tree

Christmas_tree

Snowflake (Catalan: Floquet de Neu, Spanish: Copito de Nieve, French: Flocon de Neige; c. 1964 – 24 November 2003) was the world's only known albino gorilla to date, although not the only primate. He was a western lowland gorilla. He was kept at Barcelona Zoo in Barcelona, Catalonia, Spain, from 1966 until his death.


== History ==
Snowflake was captured in the Río Muni region in Spanish Guinea on 1 October 1966 by ethnic Fang farmer Benito Mañé. Mañé had killed the rest of Snowflake's gorilla group (traditional in colour). Mañé then kept Snowflake at his home for four days before transporting him to Bata, where he was purchased by primatologist Jordi Sabater Pi.Originally named Nfumu Ngui in Fang language ("white gorilla") by his captor, he was then nicknamed Copito de nieve (Spanish for "little snowflake") by his keeper, Jordi Sabater Pi.


== Characteristics ==
Snowflake was a western lowland gorilla with non-syndromic oculocutaneous albinism. He had poor vision, though tests to determine whether he had a central blind spot did not find one. Barcelona Zoo director Antonio Jonch wrote: "The eye had a blueish sclera, a normal cornea, and a light blue iris which was very transparent to transillumination.

Snowflake (gorilla)

Snowflake_(gorilla)

Wendy's is an American international fast food restaurant chain founded by Dave Thomas on November 15, 1969, in Columbus, Ohio. The company moved its headquarters to Dublin, Ohio, on January 29, 2006. As of December 31, 2018, Wendy's was the world's third-largest hamburger fast-food chain with 6,711 locations, following Burger King and McDonald's. On April 24, 2008, the company announced a merger with Triarc Companies Inc., a publicly-traded company and the parent company of Arby's. Wendy's headquarters remained in Dublin. Following the merger, Triarc became known as Wendy's/Arby's Group, and later as The Wendy's Company.
As of December 31, 2018, there were a total of 6,711 locations, including 353 that are company-owned and 6,358 that are franchised; 92% of the system-wide locations are in North America. While Wendy's determines standards for each store's exterior appearance, food quality, and menu, the store owners have control over hours of operations, interior decor, pricing, staff uniforms, and wages.
The chain is known for its square hamburgers, sea salt fries, and Frosty, a form of soft-serve ice cream mixed with starches. Wendy's menu consists primarily of hamburgers, chicken sandwiches, French fries, and beverages such as the Frosty.

Wendy's

Wendy%27s

A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from Greek: τῆλε (tēle, far) and φωνή (phōnē, voice), together meaning distant voice. A common short form of the term is phone, which came into use almost immediately after the first patent was issued.In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice at a second device. This instrument was further developed by many others, and became rapidly indispensable in business, government, and in households.
The essential elements of a telephone are a microphone (transmitter) to speak into and an earphone (receiver) which reproduces the voice in a distant location. In addition, most telephones contain a ringer to announce an incoming telephone call, and a dial or keypad to enter a telephone number when initiating a call to another telephone. The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation. The dial may be located either on the handset or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker.

Telephone

Salar de Uyuni (or Salar de Tunupa) is the world's largest salt flat, or playa, at over 10,000 square kilometres (3,900 sq mi) in area. It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes at an elevation of 3,656 meters (11,995 ft) above sea level.The Salar was formed as a result of transformations between several prehistoric lakes. It is covered by a few meters of salt crust, which has an extraordinary flatness with the average elevation variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine, which is exceptionally rich in lithium. The large area, clear skies, and exceptional flatness of the surface make the Salar ideal for calibrating the altimeters of Earth observation satellites. Following rain, a thin layer of dead calm water transforms the flat into the world's largest mirror, 129 kilometers (80 miles) across.The Salar serves as the major transport route across the Bolivian Altiplano and is a prime breeding ground for several species of flamingos. Salar de Uyuni is also a climatological transitional zone since the towering tropical cumulus congestus and cumulonimbus incus clouds that form in the eastern part of the salt flat during the summer cannot permeate beyond its drier western edges, near the Chilean border and the Atacama Desert.Salar has been used as a filming location for movies such as Star Wars: The Last Jedi (2017; as planet Crait), The Fall (2006), Salt and Fire (2016), The Unseen (2017), and several others. 


== Formation, geology, and climate ==
Salar de Uyuni is part of the Altiplano of Bolivia in South America. The Altiplano is a high plateau, which was formed during uplift of the Andes mountains. The plateau includes fresh and saltwater lakes as well as salt flats and is surrounded by mountains with no drainage outlets.

Salar de Uyuni

Salar_de_Uyuni

Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of which have yet to be described. Most species of moth are nocturnal, but there are also crepuscular and diurnal species.


== Differences between butterflies and moths ==

While the butterflies form a monophyletic group, the moths, comprising the rest of the Lepidoptera, do not. Many attempts have been made to group the superfamilies of the Lepidoptera into natural groups, most of which fail because one of the two groups is not monophyletic: Microlepidoptera and Macrolepidoptera, Heterocera and Rhopalocera, Jugatae and Frenatae, Monotrysia and Ditrysia.Although the rules for distinguishing moths from butterflies are not well established, one very good guiding principle is that butterflies have thin antennae and (with the exception of the family Hedylidae) have small balls or clubs at the end of their antennae. Moth antennae are usually feathery with no ball on the end. The divisions are named by this principle: "club-antennae" (Rhopalocera) or "varied-antennae" (Heterocera). Lepidoptera differs between butterflies and other organisms due to evolving a special characteristic of having the tube-like proboscis in the Middle Triassic which allowed them to acquire nectar from flowering plants.


== Etymology ==
The modern English word "moth" comes from Old English "moððe" (cf. Northumbrian "mohðe") from Common Germanic (compare Old Norse "motti", Dutch "mot", and German "Motte" all meaning "moth").

Moth

Froot Loops is a brand of sweetened, fruit-flavored breakfast cereal produced by Kellogg's and sold in many countries. The cereal pieces are ring-shaped (hence "loops") and come in a variety of bright colors and a blend of fruit flavors (hence "froot", a cacography of fruit). However, there is no actual fruit in Froot Loops and they are all the same flavor. Kellogg's introduced Froot Loops in 1963. Originally, there were only red, orange and yellow loops, but green, blue and purple were added during the 1990s. Different methods of production are used in the UK where, due to the lack of natural colourings for yellow, red and blue, Froot Loops are purple, green and orange, and the loops are also larger in size. Although the marketing side of Kellogg's misleadingly sold the idea that each individual loop color was a different flavor, Kellogg's has acknowledged that all share the same fruit-blend flavor.


== Mascot ==
Toucan Sam has been the mascot of Froot Loops since its first appearance. Toucan Sam is a blue anthropomorphic toucan; the colors of his bill correspond to the three original Froot Loop colors. While toucans have a sense of smell, as most other birds, he is portrayed as having an uncanny ability to smell Froot Loops from great distances and locates a concealed bowl of the cereal while intoning "Follow my nose!

Froot Loops

Froot_Loops

The horse (Equus ferus caballus) is a domesticated one-toed hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of Equus ferus. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, Eohippus, into the large, single-toed animal of today. Humans began domesticating horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated, such as the endangered Przewalski's horse, a separate subspecies, which was once believed to be the only remaining true wild horse. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior.
Horses are adapted to run, allowing them to quickly escape predators, possessing an excellent sense of balance and a strong fight-or-flight response. Related to this need to flee from predators in the wild is an unusual trait: horses are able to sleep both standing up and lying down, with younger horses tending to sleep significantly more than adults. Female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under a saddle or in a harness between the ages of two and four.

Wiki's