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In the last two decades, photovoltaics (PV), also known as solar PV, has evolved from a pure niche market of small scale applications towards becoming a mainstream electricity source. A solar cell is a device that converts light directly into electricity using the photoelectric effect. The first solar cell was constructed by Charles Fritts in the 1880s. In 1931 a German engineer, Dr Bruno Lange, developed a photo cell using silver selenide in place of copper oxide. Although the prototype selenium cells converted less than 1% of incident light into electricity, both Ernst Werner von Siemens and James Clerk Maxwell recognized the importance of this discovery. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the crystalline silicon solar cell in 1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4.56%. By 2012 available efficiencies exceed 20% and the maximum efficiency of research photovoltaics is over 40%.
In the 1880s, who constructed the first solar cell?
A: Charles Fritts

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In the English language, the works of Shakespeare have been a particularly fertile ground for textual criticismboth because the texts, as transmitted, contain a considerable amount of variation, and because the effort and expense of producing superior editions of his works have always been widely viewed as worthwhile. The principles of textual criticism, although originally developed and refined for works of antiquity, the Bible, and Shakespeare, have been applied to many works, extending backwards from the present to the earliest known written documents, in Mesopotamia and Egypta period of about five millennia. However, the application of textual criticism to non-religious works does not antedate the invention of printing. While Christianity has been relatively receptive to textual criticism, application of it to the Jewish (Masoretic) Torah and the Qur'an is, to the devout, taboo.[citation needed]
Why is there opposition to textual criticism of Jewish and Muslim religious books?
A: is, to the devout, taboo.

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Laws dating from 17th-century colonial America defined children of African slave mothers as taking the status of their mothers, and born into slavery regardless of the race or status of the father, under partus sequitur ventrem. The association of slavery with a "race" led to slavery as a racial caste. But, most families of free people of color formed in Virginia before the American Revolution were the descendants of unions between white women and African men, who frequently worked and lived together in the looser conditions of the early colonial period. While interracial marriage was later prohibited, white men frequently took sexual advantage of slave women, and numerous generations of multiracial children were born. By the late 1800s it had become common among African Americans to use passing to gain educational opportunities as did the first African-American graduate of Vassar College Anita Florence Hemmings. Some 19th-century categorization schemes defined people by proportion of African ancestry: a person whose parents were black and white was classified as mulatto, with one black grandparent and three white as quadroon, and with one black great-grandparent and the remainder white as octoroon. The latter categories remained within an overall black or colored category, but before the Civil War, in Virginia and some other states, a person of one-eighth or less black ancestry was legally white. Some members of these categories passed temporarily or permanently as white.
What makes a person mulatto?
A: parents were black and white

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Following (or leading up to) the schisms, each Sangha started to accumulate an Abhidharma, a detailed scholastic reworking of doctrinal material appearing in the Suttas, according to schematic classifications. These Abhidharma texts do not contain systematic philosophical treatises, but summaries or numerical lists. Scholars generally date these texts to around the 3rd century BCE, 100 to 200 years after the death of the Buddha. Therefore the seven Abhidharma works are generally claimed not to represent the words of the Buddha himself, but those of disciples and great scholars.[note 38] Every school had its own version of the Abhidharma, with different theories and different texts. The different Abhidharmas of the various schools did not agree with each other. Scholars disagree on whether the Mahasanghika school had an Abhidhamma Pitaka or not.[note 38]
What is a detailed scholastic reworking of doctrinal material called?
A:
Abhidharma