Problem: Antenna (radio):

The actual antenna which is transmitting the original wave then also may receive a strong signal from its own image from the ground. This will induce an additional current in the antenna element, changing the current at the feedpoint for a given feedpoint voltage. Thus the antenna's impedance, given by the ratio of feedpoint voltage to current, is altered due to the antenna's proximity to the ground. This can be quite a significant effect when the antenna is within a wavelength or two of the ground. But as the antenna height is increased, the reduced power of the reflected wave (due to the inverse square law) allows the antenna to approach its asymptotic feedpoint impedance given by theory. At lower heights, the effect on the antenna's impedance is very sensitive to the exact distance from the ground, as this affects the phase of the reflected wave relative to the currents in the antenna. Changing the antenna's height by a quarter wavelength, then changes the phase of the reflection by 180°, with a completely different effect on the antenna's impedance.

What is altered because of the proximity to the ground?
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A: antenna's impedance


Problem: After the construction was complete there was no further room for expansion at Les Corts. Back-to-back La Liga titles in 1948 and 1949 and the signing of László Kubala in June 1950, who would later go on to score 196 goals in 256 matches, drew larger crowds to the games. The club began to make plans for a new stadium. The building of Camp Nou commenced on 28 March 1954, before a crowd of 60,000 Barça fans. The first stone of the future stadium was laid in place under the auspices of Governor Felipe Acedo Colunga and with the blessing of Archbishop of Barcelona Gregorio Modrego. Construction took three years and ended on 24 September 1957 with a final cost of 288 million pesetas, 336% over budget.
When did Barcelona sign Kubala?
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Answer: June 1950


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Miami is home to one of the largest ports in the United States, the PortMiami. It is the largest cruise ship port in the world. The port is often called the "Cruise Capital of the World" and the "Cargo Gateway of the Americas". It has retained its status as the number one cruise/passenger port in the world for well over a decade accommodating the largest cruise ships and the major cruise lines. In 2007, the port served 3,787,410 passengers. Additionally, the port is one of the nation's busiest cargo ports, importing 7.8 million tons of cargo in 2007. Among North American ports, it ranks second only to the Port of South Louisiana in New Orleans in terms of cargo tonnage imported/exported from Latin America. The port is on 518 acres (2 km2) and has 7 passenger terminals. China is the port's number one import country, and Honduras is the number one export country. Miami has the world's largest amount of cruise line headquarters, home to: Carnival Cruise Lines, Celebrity Cruises, Norwegian Cruise Line, Oceania Cruises, and Royal Caribbean International. In 2014, the Port of Miami Tunnel was completed and will serve the PortMiami.
How many square meters is PortMiami?
A: unanswerable


Context and question: The Cork area has seen improvements in road infrastructure in recent years. For example, the Cork South Link dual carriageway was built in the early 1980s, to link the Kinsale Road roundabout with the city centre. Shortly afterwards, the first sections of the South Ring dual carriageway were opened. Work continued through the 1990s on extending the N25 South Ring Road, with the opening of the Jack Lynch Tunnel under the River Lee being a significant addition. The Kinsale Road flyover opened in August 2006 to remove a bottleneck for traffic heading to Cork Airport or Killarney. Other projects completed at this time include the N20 Blackpool bypass and the N20 Cork to Mallow road projects. The N22 Ballincollig dual carriageway bypass, which links to the Western end of the Cork Southern Ring road was opened in September 2004. City Centre road improvements include the Patrick Street project - which reconstructed the street with a pedestrian focus. The M8 motorway links Cork with Dublin.
What was the purpose of the Kinsale Road flyover?
Answer: remove a bottleneck for traffic heading to Cork Airport or Killarney


Question: One of the problems of the standard electric light bulb is filament notching due to evaporation of the filament. Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and some nitrogen, or sometimes krypton. Lamps operated on direct current develop random stairstep irregularities on the filament surface which may cut lifespan in half compared to AC operation; different alloys of tungsten and rhenium can be used to counteract the effect.
Is there an answer to this question: Which type of alloys can decrease "stairstep" irregularities in light bulb filaments?

Answer: alloys of tungsten and rhenium


QUES: Tennessee was admitted to the Union on June 1, 1796 as the 16th state. It was the first state created from territory under the jurisdiction of the United States federal government. Apart from the former Thirteen Colonies only Vermont and Kentucky predate Tennessee's statehood, and neither was ever a federal territory. The state boundaries, according to the Constitution of the State of Tennessee, Article I, Section 31, stated that the beginning point for identifying the boundary was the extreme height of the Stone Mountain, at the place where the line of Virginia intersects it, and basically ran the extreme heights of mountain chains through the Appalachian Mountains separating North Carolina from Tennessee past the Indian towns of Cowee and Old Chota, thence along the main ridge of the said mountain (Unicoi Mountain) to the southern boundary of the state; all the territory, lands and waters lying west of said line are included in the boundaries and limits of the newly formed state of Tennessee. Part of the provision also stated that the limits and jurisdiction of the state would include future land acquisition, referencing possible land trade with other states, or the acquisition of territory from west of the Mississippi River.

Which state was the first formed out of federally controlled territory?
What is the answer?
ANS:
Tennessee