Article: Most common glass contains other ingredients to change its properties. Lead glass or flint glass is more 'brilliant' because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index. Thorium oxide gives glass a high refractive index and low dispersion and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern eyeglasses.[citation needed] Iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs UV wavelengths.

Question: How does barium affect glass?
Ans: increases the refractive index


Article: After the Kangxi Emperor's death in the winter of 1722, his fourth son, Prince Yong (雍親王), became the Yongzheng Emperor. In the later years of Kangxi's reign, Yongzheng and his brothers had fought, and there were rumours that he had usurped the throne(most of the rumours believe that Yongzheng's brother Yingzhen (Kangxi's 14th son) is the real successor of Kangxi Emperor, the reason why Yingzhen failed to sit on the throne is because Yongzheng and his confidant Keduo Long tampered the content of Kangxi's testament at the night when Kangxi passed away), a charge for which there is little evidence. In fact, his father had trusted him with delicate political issues and discussed state policy with him. When Yongzheng came to power at the age of 45, he felt a sense of urgency about the problems which had accumulated in his father's later years and did not need instruction in how to exercise power. In the words of one recent historian, he was "severe, suspicious, and jealous, but extremely capable and resourceful," and in the words of another, turned out to be an "early modern state-maker of the first order."

Question: Who took Kangxi's place?
Ans: Prince Yong


Article: While there is no convincing evidence for meditation in pre-Buddhist early Brahminic texts, Wynne argues that formless meditation originated in the Brahminic or Shramanic tradition, based on strong parallels between Upanishadic cosmological statements and the meditative goals of the two teachers of the Buddha as recorded in the early Buddhist texts. He mentions less likely possibilities as well. Having argued that the cosmological statements in the Upanishads also reflect a contemplative tradition, he argues that the Nasadiya Sukta contains evidence for a contemplative tradition, even as early as the late Rig Vedic period.

Question: What contains evidence for a contemplative tradition?
Ans: Nasadiya Sukta


Article: Electrical recording preceded electrical home reproduction because of the initial high cost of the new system. In 1925, the Victor company introduced the Victor Orthophonic Victrola, an acoustical record player that was specifically designed to play electrically recorded discs, as part of a line that also included electrically reproducing Electrolas. The acoustical Orthophonics ranged in price from US$95 to US$300, depending on cabinetry; by comparison, the cheapest Electrola cost US$650, the price of a new Ford automobile in an era when clerical jobs paid about $20 a week.

Question: What was a drawback of early home recording systems?
Ans:
high cost