Техническое чтение для энергетиков. Бухарова Г.П. - 89 стр.

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91
scientists in the early 1900's. Since about 1918, electric bulbs have been filled with
gas; today, a mixture of argon and nitrogen is in general use.
Is the incandescent lamp now also on its way out? In innumerable offices,
factories, public buildings and vehicles, and a good many homes (especially in the
kitchens) the fluorescent lamp has taken over from it. This is based on two scientific
phenomena that have long been known: that certain materials can be excited to
fluorescence by ultra-violet radiation, and that an electric discharge through mercury
under low pressure produces a great deal of invisible ultra-violet radiation. Professor
Becquerel, grandfather of the scientist whose work on uranium rays preceded the
discovery of radium, attempted to construct a fluorescent lamps as long ago as 1859
by using a discharge tube. American, German and other French physicists worked on
the same lines, and eventually the new type of lamp found its first applications for
abvertising (neon light). The difficulty was the production of a daylight-type of light
with sufficient blue in its spectrum.
The modern fluorescent lamp consists of a long, gas-filled glass tube, coated
inside with some fluorescent powder; this lights up when excited by the invisible
ultraviolet rays of an arc passing from the electrode at one end to that at the other.
Strip lighting is extremely efficient and needs little current because it works 'cold' – i.
e. very little electrical energy is turned into waste heat as in incandescent lamps. It is
roughly fifty times more effective than Edison's first carbon-filament lamps.
The mercury or sodium vapour lamps which are now used on the roads are
'discharge' lamps, invented in the early 1930's. They have a 'conductor' in the form of
a gas or metallic vapour at low pressure; this is raised to incandescence by the electric
current, and emits light of one characteristic colour, greenish-blue (mercury vapour)
or yellow (sodium vapour). They are 'monochrome' lamps, that is, they emit light of
only one colour, which makes it easier for the motorist to distinguish objects on the
roads; it is also less scattered by mist or fog. True, that light makes people look like
ogres – but it makes our streets definitely safer by night.
THE STEAM TURBINE
It is most important to remember that electricity is only a means of distributing
energy, of carrying it from the place where it is produced to the places where it is
used. It is not a 'prime mover' like the steam-engine or even the water mill. A
generator is no use at all unless it is rotated by a prime mover. During the' first few
years of electric power there was no other way of moving the generators than either
by the force of falling water or by ordinary steam-engines.
Soon, however, there came a new and very efficient prime mover, the steam-
turbine.
The steam-turbine must be a much more efficient and powerful prime mover
than the reciprocating engine because it must short-cut the complicated process of
converting steam energy into rotary motion via reciprocating motion. But the
problems involved in building such a machine seemed formidable, especially that of
high-precision engineering. It was only towards the end of the nineteenth century that

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