Problem: Incandescent light bulb:

To improve the efficiency of the lamp, the filament usually consists of multiple coils of coiled fine wire, also known as a 'coiled coil'. For a 60-watt 120-volt lamp, the uncoiled length of the tungsten filament is usually 22.8 inches (580 mm), and the filament diameter is 0.0018 inches (0.046 mm). The advantage of the coiled coil is that evaporation of the tungsten filament is at the rate of a tungsten cylinder having a diameter equal to that of the coiled coil. The coiled-coil filament evaporates more slowly than a straight filament of the same surface area and light-emitting power. As a result, the filament can then run hotter, which results in a more efficient light source, while reducing the evaporation so that the filament will last longer than a straight filament at the same temperature.

What is the advantage of a coiled-coil filament over a straight filament?
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A: The coiled-coil filament evaporates more slowly


Problem: Boston:

In 1950, whites represented 94.7% of Boston's population. From the 1950s to the end of the 20th century, the proportion of non-Hispanic whites in the city declined; in 2000, non-Hispanic whites made up 49.5% of the city's population, making the city majority-minority for the first time. However, in recent years the city has experienced significant gentrification, in which affluent whites have moved into formerly non-white areas. In 2006, the US Census Bureau estimated that non-Hispanic whites again formed a slight majority. But as of 2010, in part due to the housing crash, as well as increased efforts to make more affordable housing more available, the minority population has rebounded. This may also have to do with an increased Latino population and more clarity surrounding US Census statistics, which indicate a Non-Hispanic White population of 47 percent (some reports give slightly lower figures).

What year did non hispanic whites once again become the majority of the population?
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A: 2006


Problem: Galicia (Spain):

The oldest attestation of human presence in Galicia has been found in the Eirós Cave, in the municipality of Triacastela, which has preserved animal remains and Neanderthal stone objects from the Middle Paleolithic. The earliest culture to have left significant architectural traces is the Megalithic culture which expanded along the western European coasts during the Neolithic and Calcolithic eras. Thousands of Megalithic tumuli are distributed throughout the country, but mostly along the coastal areas. Within each tumulus is a stone burial chamber known locally as anta (dolmen), frequently preceded by a corridor. Galicia was later fully affected by the Bell Beaker culture. While its rich mineral deposits - tin and gold - led to the development of Bronze Age metallurgy, and to the commerce of bronze and gold items all along the Atlantic façade of Western Europe, where a common elite's culture evolved during the Atlantic Bronze Age.

Which two minerals found in abundance in Galicia were used during Bronze Age?
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A: tin and gold


Problem: Education:

Educational psychology is the study of how humans learn in educational settings, the effectiveness of educational interventions, the psychology of teaching, and the social psychology of schools as organizations. Although the terms "educational psychology" and "school psychology" are often used interchangeably, researchers and theorists are likely to be identified as educational psychologists, whereas practitioners in schools or school-related settings are identified as school psychologists. Educational psychology is concerned with the processes of educational attainment in the general population and in sub-populations such as gifted children and those with specific disabilities.

What is the meaning of Education psychology?
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A:
the study of how humans learn in educational settings