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Medicine in the Eighteenth Century. University of Kansas Press. |
Medicine in the Eighteenth Century. University of Kansas Press. |


[http://kuscholarworks.ku.edu/dspace/bitstream/1808/6347/1/upk.vesalius
[http://kuscholarworks.ku.edu/dspace/bitstream/1808/6347/1/upk.vesalius_four_centuries_later.pdf PDF].</ref> <ref name=Fulton group=Note/>
 
_four_centuries_later.pdf Full-Text PDF].</ref> <ref name=Fulton group=Note/>


===Notes===
===Notes===

Revision as of 18:56, 9 September 2011

Introduction

Consider this approach to defining ‘electric charge’:

  • Electric charge is a property of matter manifesting in certain of the particle constituents of matter.
  • At one level of explanation of matter, matter consists of atoms.
  • Studying atoms at the first layer of their substructure, viz., the nucleus and surrounding electrons, can provide a fruitful basis for explaining electric charge.
  • As a starting point, note that:
    • Electrons can maintain their location surrounding and revolving about the nucleus only because a radial force of attraction on them exists directed toward the nucleus. Otherwise the electrons would fly off.
  • Experiments reveal that:
    • The force of attraction between the electrons and the nucleus greatly exceeds the gravitational force generated by the masses of the two groups of particles;
    • Therefore a force differing from the force of gravitation is operating, requiring a new designation;
      • For historical reasons discussed later, we designate the force an ‘electric force’.

...the electric force is approximately 42 orders of magnitude larger than the gravitational force. To see the enormity of this ratio, suppose that we represent the gravitational force by an arrow as long as a bacterium. How long would the length of the electric arrow be? Much larger than the height of a man; much taller than the Empire State Building; much larger than the Earth itself; much larger than the solar system; and much larger than the Milky Way. In fact, the electric arrow would be over 10 billion times larger than the "size" of the visible universe! That is why, when electrical forces are present, gravitational forces can be completely ignored.[1]

  • Experiments reveal also that:
    • The force of attraction occurs between the protons in the nucleus and the surrounding electrons, the two groups normally equal in number;
    • The magnitude of the electric force varies inversely with the square of the distance of separation over which the force operates.
  • Experiments reveal also that:
    • The electric force between two spatially separate protons is one of repulsion rather than of attraction;
    • The electric force between two spatially separate electrons likewise is one of repulsion rather than of attraction;
    • When separated by the same distance, the magnitude of the electric force is the same between a proton and an electron, a proton and a proton, and an electron and an electron.
  • Those experiments permit the conclusions that:
    • The electric force can be one either of attraction or repulsion;
    • Given that protons and electrons differ in mass by several orders of magnitude, the electric force does not depend on the masses of the interacting particles;
    • Therefore some quantitative property other than mass must generate and respond to the electric force between interacting particles;
      • call it ‘electric charge’, and symbolize its unit of magnitude, q.
    • The ‘quality’ of the proton’s electric charge must differ from the ‘quality’ of the electron’s electric charge, otherwise protons and electrons could not generate and respond to either an attractive or repellent electric force depending on which interacts with which;
      • call the quality of the proton’s electric charge ‘positive’ and that of the electron’s ‘negative’, in keeping with historical designations arbitrarily assigned during the history of studies of electric phenomena on the macroscopic scale.
  • From the above discussion, we can formulate a provisional working definition of electric charge as follows:

Electric charge is a property of matter manifesting with an attribute of one or the other of opposite extremes, arbitrarily referred to as positive and negative, characteristic of certain of its constituent subatomic particles—specifically, protons (positive) and electrons (negative)—the property having the fundamental characteristic of producing and responding to a force of attraction between positive and negative, or of repulsion between positive and positive and between negative and negative, the force acting on spatially separated particles, that force, called the 'electric force', having a strength many orders of magnitude greater than that of the force of gravity.

  • Atoms of the chemical elements heavier than hydrogen...

Continue in this vein....

References

Older

Once you have established those basic ideas about electricity, "like charges repel and unlike charges attract", then you have the foundation for electricity and can build from there.
—Electric Charge, Hyperphysics Online

In reference to the physics and chemistry of electricity, charge, or more specifically, electric charge, is a fundamental property of matter that causes matter having that property to generate and react to a force of attraction or repulsion to spatially separate matter that likewise manifests the property of electric charge.[1] [2] [3]

Whatever constitutes electric charge constitutes it as two separate qualities, or polarities, assigned the names 'positive' and 'negative', or 'plus' and 'minus'. The attractive force between electrically charged entities arises between oppositely-charged entities—positive-negative—whereas the repulsive force arises between like-charged entities—positive-positive, or negative-negative.

Familiar examples of positively charged matter are protons, constituents of the nuclei of atoms, and familiar examples of negatively charged matter are electrons, constituents of atoms that surround their nuclei.

Given that the terms 'positive' and 'negative' serve only as labels to distinguish the two polarities observed in the electric charge of matter, 'positivity' and 'negativity' do not themselves imply anything about the fundamental nature of electric charge. Other labels connoting bi-polarity, such as yin/yang, black/white, or bitter/sweet, could serve for labeling.

The atoms that comprise the chemical elements of the periodic table, while consisting in part of the electrically charged particles, protons and electrons, do not themselves manifest an electric charge, because protons in the nuclei and the surrounding electrons are equal in number and quantity of charge, that balance ensuring that the atoms as a whole manifest no net electric charge—a state referred to as electrical neutrality.

Discovery and naming of electric charge

The ancient Greeks as far back as the beginning of the 6th century BCE, beginning with Thales of Miletus, had observed some of the simple phenomenology related to electric charge, Thales demonstrating it using the fossilized tree resin, amber, rubbed with cloth:[4] [5]

That little piece of amber rubbed by Thales, some 2,500 years ago, appeared then to be very insignificant. Had the world but known, it was fraught with vast possibilities; for, in point of fact, Thales had unconsciously rediscovered Aladdin's Wonderful Lamp. As he rubbed, the Genie of electricity appeared, and demanded, "What wouldst thou have? I am ready to obey thee as the slave of the lamp, I and the other slaves of the lamp." But the question remained unanswered. Neither Thales nor the witnesses of his experiment made any request nor asked its genii to aid them. They had ears, but they heard not, and so the genie disappeared, with all that he was both willing and able to do left undone.
—E.J. Houston, 1905[4]

In 600 B.C. Thales, erudite philosopher and astronomer in the thriving Ionian port of Miletus, observed the special qualities of the rare yellow orange amber, jewel-like in its hardness and transparency. If rubbed briskly with a cloth, Thales showed, amber seemed to come alive, causing light objects—like feathers, straw, or leaves—to fly toward it, cling, and then gently detach and float away. Amber was similar to a magnet in its qualities, yet it was not a lodestone. As a youth, Thales of Miletus had studied in the sacred Egyptian cities of Memphis and Thebes. Perhaps it was there, under the burning sun, that this earliest of Greek philosophers first learned from the priests about the prized amber, with its seeming possession of a soul.[5]

Thales, it appears, believed amber an animate thing, something with soul.[6]

The Greek word for amber, elektron, ultimately through Latin, electrum, gave rise to the English words, electrical and electric — words used to refer to the amber phenomenon before the publication of William Gilbert's landmark work, De magnete, in 1600, describing the results of the first systematic experimental studies of magnetic and electrical phenomena in Western science.[7] [8]

The word, charge, used in its electrical sense, was first used by Benjamin Franklin, in 1747, as a verb, and subsequently by him as adjective and noun:

Our spheres are fixed on iron axes, which is passed through them. At one and of the axis there is a small handle, with which you turn the sphere like a common grindstone. This we find very commodious, as the machine takes up little room, is portable, and may be enclosed in a tight box, when not in use. 'Tis true, the sphere does not turn so swift as when the great wheel is used, but swiftness we think of little importance, since a few turns will charge the phial, etc., sufficiently. [italics added] [9]

Presumably, Franklin, who, in his many writings, frequently used the word, charge, and its variant forms (charging, charged, etc.), in its non-electrical sense, had in mind the word's sense of 'loading' or 'filling' something:

charge - ORIGIN: Middle English (in the general senses ‘to load’ and ‘a load’): from Old French charger (verb), charge (noun), from late Latin carricare, carcare ‘to load,’ from Latin carrus ‘wheeled vehicle.’...Examples: load or fill (a container, gun, etc.) to the full or proper extent: will you see to it that your glasses are charged? | fill or pervade (something) with a quality or emotion: the air was charged with menace.[10]

References

  1. Gibilisco S. (2005) Electricity Demystified. New York: McGraw-Hill. | Stan Gibilisco is an electronics engineer and mathematician, author of numerous technical books on electronics and mathematics.
  2. Elert G. (1998-2010) Electric Charge: Summary. The Physics Hypertextbook.
  3. Elert G. (1998-2010) Electric Charge. The Physics Hypertextbook.
  4. 4.0 4.1 Houston EJ. (1905) Electricity in every-day life. New York: P. F. Collier & Son, 1905. | Title link: Google Book Full-Text Volume 1 of 3.
    • That little piece of amber rubbed by Thales, some 2,500 years ago, appeared then to be very insignificant. Had the world but known, it was fraught with vast possibilities; for, in point of fact, Thales had unconsciously rediscovered Aladdin's Wonderful Lamp. As he rubbed, the Genie of electricity appeared, and demanded, "What wouldst thou have? I am ready to obey thee as the slave of the lamp, I and the other slaves of the lamp." But the question remained unanswered. Neither Thales nor the witnesses of his experiment made any request nor asked its genii to aid them. They had ears, but they heard not, and so the genie disappeared, with all that he was both willing and able to do left undone.
  5. 5.0 5.1 Jonnes J. (2004) Empires of Light: Edison, Tesla, Westinghouse, and the Race to Electrify the World. Random House Digital, Inc. ISBN 0375758844. | Title link: a Google Books extract.
  6. Barnes J. (1982) The Presocratic Philosophers'. Psychology Press. ISBN 978041505079. | Title link: Google Book extract.
  7. Electric. Webster's Third New International Dictionary, Unabridged. Merriam-Webster, 2002.
  8. Gilbert W. (1600, 1958) De magnete. Republication of the first English translation, from Gilbert's original in Latin, by P. Fleury Mottelay, in 1893. Courier Dover Publications. ISBN 9780486267616. | Google Books extract.
  9. Franklin B. (1769) Experiments And Observations On Electricity, Made At Philadelphia in America: To which are added, Letters and Papers On Philosophical Subjects. David Henry, publisher. | Google Books Full-Text.
    • See pages 311 for Franklin's 1747 letter to Peter Collinson, with Franklin's first use of 'charge'.
  10. charge v.. New Oxford American Dictionary. Edited by Angus Stevenson and Christine A. Lindberg. Oxford University Press, 2010. Oxford Reference Online. Oxford University Press. Accessed. 3 July 2011.



Test

text[1] [Note 1]

Notes

  1. Historian John F. Fulton quotes Vesalius as exclaiming:

    I acknowledge no authority save the witness of mine own eyes—I must have the liberty to compare the dicta of Galen with the observed facts of bodily structure.

refs

  1. Fulton JF. (1950) Vesalius Four Centuries Later. Logan Clendening Lectures on the History and Philosophy of Medicine, First Series: i Vesalius Four Centuries Later; ii Medicine in the Eighteenth Century. University of Kansas Press. | PDF.