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 History of Electrostatic Generators تاريخ اختراع مولد الشحنات

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مُساهمةموضوع: History of Electrostatic Generators تاريخ اختراع مولد الشحنات   السبت يوليو 17, 2010 12:20 pm

تاريخ اختلراع مولد الشحنات History of Electrostatic Generators
History of Electrostatic Generators




Today, everybody is familiar with electricity. Let's say, almost
everybody uses electricity as a ready-for-use energy that is provided
in a clean way. This is the result of long research and engineering
work which can be traced back for centuries. The first generators of
electricity were not electrodynamic as today's machines, but they were
based on electrostatic principles. Long before electrodynamic
generators were invented, electrostatic machines and devices had their
place in science. Due to their principle of operation, electrostatic
generators produce high voltage, but low currents. The output is always
a unipolar static voltage. Depending from the used materials, it may be
positve or negative.
Friction is the key of the operation! Although most mechanical energy
needed to power an electrostatic generator is converted into heat, a
fraction of the work (not a fraction of friction - got the point?) is
used to generate electric potential by splitting charges. The Beginnings


In ancient greece, the amber was known to attract little objects after
being rubbed with cloth or fur. From the Greek expression elektron, the
modern term electrics is directly derived. In 1600, William Gilbert (1544-1603) coined the expression electrica in his famous book De Magnete.
In ancient Greece, there was no effort to mechanize the rubbing of a
piece of amber in order to get a continous effect. Although light could
be observed in the dark, nobody made a connection between this and the
lightning which was regarded as Zeus' weapon. The knowledge about this
type of electricity remained almost unchanged until the beginning of
the seventeenth century. Several antique authors like Pliny the elder
or Renaissance men like Giovanni Battista della Porta describe the
effect but without drawing further conclusions. The Sulphur Ball

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

Otto von Guericke (1602-1686) who became famous for his Magdeburg
vacuum experiments invented a first simple electrostatic generator. It
was made of a sulphur ball which rotated in a wooden cradle. The ball
itself was rubbed by hand. As the principles of electric conduction had
not been discovered yet, von Guericke transported the charged sulphur
ball to the place where the electric experiment should happen.

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]
von Guericke's first electrostatic generator around 1660

Guericke made the ball by pouring molten sulphur into a hollow glass
sphere. After the sulphur was cold, the glass hull was smashed and
removed. Some day, a researcher found out that the empty glass sphere
itself provided the same results. A Baroque Gas Discharging Lamp


In 1730 scientific research has discovered the principles of electric
conduction. An inspiriation for electric research came from an area
which at the first glance had absoluteley nothing to contribute: the
mercury barometric device invented by Evangelista Torricelli. If the
mercury-filled tube was shaken and the evacuated portion of the tube
was observed in the dark, a light emission could be seen. William
Hauksbee, both inventive and inquisitive, designed a rotor to rub a
small disk of amber in a vacuum chamber. When the chamber contained
some mercury vapour, it lit up! This was the first mercury gas
discharge lamp! The engravings show surprising similarities to today's
lightning spheres

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

Hauksbee's amber rotor
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]
Hauksbee's setup to demonstrate
light effects caused by static electricity.
The Beer Glass Generator


Glass proved to be an ideal material for an electrostatic generator. It
was cheaper than sulphur and could easily be shaped to disks or
cylinders. An ordinary beer glass turned out to be a good isolating
rotor in Winkler's electrostatic machine

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

An electrostatic machine invented by
Johann Heinrich Winkler (1703-1770

)

Machines like these were not only made for scientific research, but a
preferred toy for amusement. In the 18th century, everybody wanted to
experience the electric shock. Experiments like the "electric kiss"
were a salon pastime. Although the French Abbé Nollet demonstrated in
1745 that little animals like birds and fish were killed
instantaneuosly by the discharge of a Leyden jar, nobody was aware of
the latent dangers of this type of experiments

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

The electric kiss provided a very special thrill

Soon after the effects of electrostatic discharge were found,
researchers and charlatans started to cure diseases with electric
shocks. Here we find parallels to the "Mesmerists" who claimed to use
magnetic powers for therapy

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

Toothache therapy around 1750
Being ill at that time was no fun!
The Leyden Jar


In 1745, the so-called Leyden Jar
(or Leyden Bottle) was invented by Ewald Jürgen von Kleist (1700-1748).
Kleist searched for a way to store electric energy and had the idea to
fill it into a bottle! The bottle contained water or mercury and was
placed onto a metal surface with ground connection. No wonder: the
device worked, but not because of the fact that electricity could be
filled into bottles.One year after Kleist, the physicist Cunnaeus in
Leyden/the Netherlands independently invented this bottle again. Thus
the term Leyden Jar became more familiar, although in Germany, this device sometimes also was called Kleist's bottle.

An intense research work began to find out which liquid is the most
suitable. A few years later, researchers had learned that water is not
necessary, but a metal hull inside and outside the jar was sufficient
for storing electrostatic energy. Thus the first capacitors were born.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة][ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

Early Leyden jarsAn advanced electrostatic battery in 1795


Frequently, several jars were connected in order to multiply the
charge. Experimenting with this type of capacitors started to become
pretty dangerous. In 1783, while trying to charge a battery during a
thunderstorm, Prof. Richmann was killed by unintendedly getting too
close to a conductor with his head. He is the first known victim of
high voltage experiments in the history of physics. Benjamin Franklin
had a good deal of luck not to win this honour when performing his kite
experiments

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

St. Petersburg, 6 August 1783. Prof. Richman and his assistant being
struck by lightning while charging capacitors. The assistant escaped
almost unharmed, whereas Richman was dead immediately. The pathologic
analysis revealed that "he only had a small hole in his forehead, a
burnt left shoe and a blue spot at his foot. [...] the brain being ok,
the front part of the lung sane, but the rear being brown and black of
blood." The conclusion was that the electric discharge had taken its
way through Richmann's body. The scientific community was shocked.

The Disk Rotor


Generators based on disks were invented around 1800 by Winter. Their
characteristic construction element is a mercury-prepared leather
cushion that covers approximately one forth of the surface area. The
leather cushion replaced the experimentor's hand and gave a more
continous result. In 1799, first experiments of electrolysis by
electrostatic energy were made. It turned out that the recently
invented chemical elements caused same or better effect than many
thousand electric discharges of a Leyden bottle battery. Experiments
like these helped to shape the understanding of electric energy

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

An early disk generator by Winter
The Advanced Rotor


Inventors found out that it is a good idea to laminate metal or
cardboard sheets onto the isolating disks of electrostatic generators

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

The so-called influence machine by Holtz, 1865
Disks for advanced generators of this type were made of glass, shellac
and ebonite (hard rubber). Especially hard rubber turned out to be a
very suitable material as it did not get damaged so easily than glass
or shellac.

The Wimshurst Machine


Wimshurst machines are the end point of the long development of
electrostatic disk machines. They caused very good results and were
frequently used to power X-ray tubes. The characteristic construction
element of these machines are disks which are laminated with radially
arranged metal sheets. The advantage of disks is that they can be
stacked onto one axle in order to multiply the effect


.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A Wimshurst machine around 1905.
The end point of a long development

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]


The invention of the electomagnetic inductor by Ruhmkorff in 1857 began
to make the electrostatic disk machines obsolete. Today, both devices
only serve as useful demonstration objects in physics lessons to show
how electric charges accumulate. For technical applications, high
voltages can be easier generated by electronic and electromagnetic
methods.

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]
A Ruhmkorff inductor to power an X-ray tube (1910)
The Van-DeGraaff Generator


The principle of this machine is to transport voltage by the aid of a
tape made of isolating flexible material e.g. rubber. Early in the
development of machinery, it was observed that mechanical transmission
belts gave reason for unintended high voltage production, which harmed
persons or buildings by igniting parts of a workshop. The same effect
caused by transporting the highly inflammable celluloid films inside
the projector was the reason for more than one cinema perishing in fire

.
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A 5 Megavolt Van-deGraaff generator

The principle is based on an isolating endless tape which transports an
electric charge to a conductor. Although the device can be operated
without an additional electric power source, normally a DC high voltage
is applied to the tape, thus considerably increasing the output
voltage. Van DeGraaff generators are still in use in particle
accellerator labs. The largest machines produce up to 10 million Volts.
The Steam Electrostatic Generator


Wet steam which is pressed through a nozzle causes electric chargement.
This was the origin of the idea to construct an electrostatic generator
based on steam. Although these machines caused good results, they were
difficult to maintain. As they also were expensive, comparatively few
were built and have survived in museum collections

. [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A steam electrostatic generator




Conclusion


Electrostatic generators have their place in the history of science.
They accompanied the way to understand electricity. However, their
efficiency is poor, compared to the mechanical effort which is needed
to produce electrical energy. In this context, I'd like to seriously
warn all would-be inventors of electrostatic PMMs based on disk rotors
or on the Van deGraaf principle. Machines of this type are no toy and
even small devices can be dangerous if carelessly handled. As a rule of
thumb, a charged Leyden jar of 1/2 liter (=1/8 gallon) volume can
endanger your life

_________________
الأندلس ( الفردوس المفقود )
{{ ابك مثل النساء ملكا مضاعا لم تحافظ عليه مثل الرجال }}
في 2 يناير 1492 م سقطت مدينة "غرنـــــاطة" آخر مدن الأندلس المسلمة، ورفع العلم الصليبي على قصر الحمراء فيها!
اللهم أغفر للمؤمنين والمؤمنات والمسلمين والمسلمات الأحياء منهم والأموات
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]
اللهم ان لك صفوة تدخلهم الجنة من غير حساب ولا عقاب
فاجعلني و قارئ الموضوع منهم

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History of Electrostatic Generators تاريخ اختراع مولد الشحنات
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