Problem: During ordinary operation, the tungsten of the filament evaporates; hotter, more-efficient filaments evaporate faster. Because of this, the lifetime of a filament lamp is a trade-off between efficiency and longevity. The trade-off is typically set to provide a lifetime of several hundred to 2,000 hours for lamps used for general illumination. Theatrical, photographic, and projection lamps may have a useful life of only a few hours, trading life expectancy for high output in a compact form. Long-life general service lamps have lower efficiency but are used where the cost of changing the lamp is high compared to the value of energy used.
What is the typical tradeoff in light bulb design?
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Answer: efficiency and longevity

Problem: In 1897, Victoria had written instructions for her funeral, which was to be military as befitting a soldier's daughter and the head of the army, and white instead of black. On 25 January, Edward VII, the Kaiser and Prince Arthur, Duke of Connaught, helped lift her body into the coffin. She was dressed in a white dress and her wedding veil. An array of mementos commemorating her extended family, friends and servants were laid in the coffin with her, at her request, by her doctor and dressers. One of Albert's dressing gowns was placed by her side, with a plaster cast of his hand, while a lock of John Brown's hair, along with a picture of him, was placed in her left hand concealed from the view of the family by a carefully positioned bunch of flowers. Items of jewellery placed on Victoria included the wedding ring of John Brown's mother, given to her by Brown in 1883. Her funeral was held on Saturday, 2 February, in St George's Chapel, Windsor Castle, and after two days of lying-in-state, she was interred beside Prince Albert in Frogmore Mausoleum at Windsor Great Park. As she was laid to rest at the mausoleum, it began to snow.
What was placed in the Queens left hand when she was placed in her coffin?
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Answer: a lock of John Brown's hair

Problem: Zinc is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish. It is somewhat less dense than iron and has a hexagonal crystal structure, with a distorted form of hexagonal close packing, in which each atom has six nearest neighbors (at 265.9 pm) in its own plane and six others at a greater distance of 290.6 pm. The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 C. Above 210 C, the metal becomes brittle again and can be pulverized by beating. Zinc is a fair conductor of electricity. For a metal, zinc has relatively low melting (419.5 C) and boiling points (907 C). Its melting point is the lowest of all the transition metals aside from mercury and cadmium.
Is iron more dense than zinc?
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Answer:
It is somewhat less dense than iron