Input: Article: The current–voltage characteristic of an LED is similar to other diodes, in that the current is dependent exponentially on the voltage (see Shockley diode equation). This means that a small change in voltage can cause a large change in current. If the applied voltage exceeds the LED's forward voltage drop by a small amount, the current rating may be exceeded by a large amount, potentially damaging or destroying the LED. The typical solution is to use constant-current power supplies to keep the current below the LED's maximum current rating. Since most common power sources (batteries, mains) are constant-voltage sources, most LED fixtures must include a power converter, at least a current-limiting resistor. However, the high resistance of three-volt coin cells combined with the high differential resistance of nitride-based LEDs makes it possible to power such an LED from such a coin cell without an external resistor.

Now answer this question: What feature do most LED fixtures need to have?

Output: a power converter


Article: From 1989 through 1996, the total area of the US was listed as 9,372,610 km2 (3,618,780 sq mi) (land + inland water only). The listed total area changed to 9,629,091 km2 (3,717,813 sq mi) in 1997 (Great Lakes area and coastal waters added), to 9,631,418 km2 (3,718,711 sq mi) in 2004, to 9,631,420 km2 (3,718,710 sq mi) in 2006, and to 9,826,630 km2 (3,794,080 sq mi) in 2007 (territorial waters added). Currently, the CIA World Factbook gives 9,826,675 km2 (3,794,100 sq mi), the United Nations Statistics Division gives 9,629,091 km2 (3,717,813 sq mi), and the Encyclopædia Britannica gives 9,522,055 km2 (3,676,486 sq mi)(Great Lakes area included but not coastal waters). These source consider only the 50 states and the Federal District, and exclude overseas territories.

Question: According to the CIA World Factbook, what is the total area of the US in miles?
Ans: 3,794,100 sq mi


Here is a question about this article: Nueva Vizcaya (New Biscay) was the first province of northern New Spain to be explored and settled by the Spanish. Around 1528, a group of Spaniard explorers, led by Álvar Núñez Cabeza de Vaca, first entered the actual territory of what is now Chihuahua. The conquest of the territory lasted nearly one century, and encountered fierce resistance from the Conchos tribe, but the desire of the Spanish Crown to transform the region into a bustling mining center led to a strong strategy to control the area.
What is the answer to this question: The Spanish crown wanted to turn the region into what type of industry?
****
So... mining center


The problem: Answer a question about this article:
Notre Dame rose to national prominence in the early 1900s for its Fighting Irish football team, especially under the guidance of the legendary coach Knute Rockne. The university's athletic teams are members of the NCAA Division I and are known collectively as the Fighting Irish. The football team, an Independent, has accumulated eleven consensus national championships, seven Heisman Trophy winners, 62 members in the College Football Hall of Fame and 13 members in the Pro Football Hall of Fame and is considered one of the most famed and successful college football teams in history. Other ND teams, chiefly in the Atlantic Coast Conference, have accumulated 16 national championships. The Notre Dame Victory March is often regarded as the most famous and recognizable collegiate fight song.
Which athletic association are the student athletes at Notre Dame a part of?
****
The answer: NCAA Division I


Problem: Please answer a question about the following article about Wood:
The chemical composition of wood varies from species to species, but is approximately 50% carbon, 42% oxygen, 6% hydrogen, 1% nitrogen, and 1% other elements (mainly calcium, potassium, sodium, magnesium, iron, and manganese) by weight. Wood also contains sulfur, chlorine, silicon, phosphorus, and other elements in small quantity.
What element joins potassium, calcium, manganese, iron, and sodium to make a combined 1% of the chemical composition of wood?
A: magnesium


Question: Read this and answer the question

The northern side of the borough includes the largest park in New York City—Pelham Bay Park, which includes Orchard Beach—and the fourth largest, Van Cortlandt Park, which is west of Woodlawn Cemetery and borders Yonkers. Also in the northern Bronx, Wave Hill, the former estate of George W. Perkins—known for a historic house, gardens, changing site-specific art installations and concerts—overlooks the New Jersey Palisades from a promontory on the Hudson in Riverdale. Nearer the borough's center, and along the Bronx River, is Bronx Park; its northern end houses the New York Botanical Gardens, which preserve the last patch of the original hemlock forest that once covered the entire county, and its southern end the Bronx Zoo, the largest urban zoological gardens in the United States. Just south of Van Cortlandt Park is the Jerome Park Reservoir, surrounded by 2 miles (3 km) of stone walls and bordering several small parks in the Bedford Park neighborhood; the reservoir was built in the 1890s on the site of the former Jerome Park Racetrack. Further south is Crotona Park, home to a 3.3-acre (1.3 ha) lake, 28 species of trees, and a large swimming pool. The land for these parks, and many others, was bought by New York City in 1888, while land was still open and inexpensive, in anticipation of future needs and future pressures for development.

What do the NY Botanical Gardens preserve?
Answer:
the last patch of the original hemlock forest that once covered the entire county