Техническое чтение для энергетиков. Бухарова Г.П. - 78 стр.

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80
however, he declined it and he also declined an offer of knighthood. He was intent on
being plain Michael Faraday.
JAMES MAXWELL
In the decade 1860–1870, James Maxwell formulated his classical
electromagnetic theory. He showed that light was a form of wave motion travelling
with a speed dependent on the electric and magnetic properties of the medium
through which it is transmitted, lie also predicted that waves longer than those of light
could exist.
Even before Maxwell advanced the theory that electromagnetic waves should
exist, men were making use of them for other purposes besides vision. For instance,
the short ultraviolet rays in sunlight provided suntans; and the heat of the sun –
provided by the long infra-red rays – was often concentrated by means of a lens to
start fires. After the existence of electromagnetic waves had been proved by Hertz it
was discovered that they range in length from hundreds of miles down to less than a
billionth of an inch. The long waves could be used to carry sounds through space; as
a consequence radio was developed.
A more recent development, which is related to radio, is television. Not only
sounds but pictures can be transmitted at a distance because of electromagnetic
waves.
Another modern device, developed to send out electromagnetic waves and to
receive the echoes when they return, is radar, since the speed of electromagnetic
waves is known, the time it takes for an echo to return to the radar set can tell the
operator how far away a plane is from his set. Radar is given the credit for saving
Great Britain during World War II, for it warned of enemy planes. Thus James
Maxwell had made discoveries that later protected his homeland. Today with radio,
television, radar, and communication with outer space making use of these waves, it
is easy to realize why James Maxwell is now considered one of the great scientists of
all time.
BALL LIGHTNING
It is quite probable that there are several different physical forms of ball
lightning, each having its own characteristic set of properties. These phenomena are
rare and this rarity leads to the wide variety of descriptions of ball lightning.
Lightning balls seem to appear near the end of severe electrical storms. This
happens after the air has been highly ionized and is filled with electromagnetic
disturbances generated by the conventional lightning.
The diameters of observed lightning balls range from a few inches to rare
instances of many feet. The average diameter of a ball is about 10 inches. The balls
usually move by rolling or sliding along conductors such as telephone wires, fences,
and other metallic objects.
The lifetime of a ball of lightning may range from a few seconds to minutes.

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