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insulation
insulation , use of materials or devices to inhibit or prevent the conduction of heat or of electricity. Common heat insulators are, fur, feathers, fiberglass, cellulose fibers, stone, wood, and wool; all are poor conductors of heat. The use of asbestos , formerly a common insulating material, ha...
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Samuel Insull
Samuel Insull , 1859-1938, American public utilities financier, b. London. He arrived in the United States in 1881 and was employed by Thomas A. Edison as a private secretary. He later became prominent in the management of the Edison industrial holdings. By 1907 he overcame competing public utilit...
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feather
feather One of the skin appendages that makes up the plumage of birds. They are composed of the fibrous protein keratin, and provide insulation and enable flight. They are usually replaced at least once a year....
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feather
feather One of the skin appendages that makes up the plumage of birds. They are composed of the fibrous protein keratin, and provide insulation and enable flight. They are usually replaced at least once a year....
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dielectric
dielectric , material that does not conduct electricity readily, i.e., an insulator (see insulation ). A good dielectric should also have other properties: It must resist breakdown under high voltages; it should not itself draw appreciable power from the circuit; it must have reasonable physical st...
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semiconductor
semiconductor solid material whose electrical conductivity at room temperature is between that of a conductor and that of an insulator (see conduction ; insulation ). At high temperatures its conductivity approaches that of a metal, and at low temperatures it acts as an insulator. In a semiconduc...
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cable
cable originally wire cordage of great strength or heavy metal chain used for hauling, towing, supporting the roadway of a suspension bridge, or securing a large ship to its anchor or mooring. Today a cable often refers to a line used for the transmission of electrical signals. One type of electric...
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coal tar
coal tar product of the destructive distillation of bituminous coal. Coal tar can be distilled into many fractions to yield a number of useful organic products, including benzene, toluene, xylene, naphthalene, anthracene, and phenanthrene. These substances, called the coal-tar crudes, form the star...
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Leyden jar
Leyden jar , form of capacitor invented at the Univ. of Leiden in the 18th cent. It consists of a narrow-necked glass jar coated over part of its inner and outer surfaces with conductive metal foil; a conducting rod or wire passes through an insulating stopper in the neck of the jar and contacts t...
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polyethylene
polyethylene , widely used plastic . It is a polymer of ethylene , CH 2 [symbol]CH 2 , having the formula (-CH 2 -CH 2 -) n , and is produced at high pressures and temperatures in the presence of any one of several catalysts , depending on the desired properties for the finished product. Polyet...
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