Jump to content

Electric charge

From Tilcayo Cats, the lean encyclopaedia by Tilcayo Knowledge Systems

Electric charge is a property of particles of matter, such as electrons and protons; a charge is not itself a particle.[1] There are two kinds of charge,[2] called positive and negative.[3] Objects with the same kind of charge push each other away, and objects with opposite kinds pull towards each other.[4] Unlike pushes and pulls that need touching, this electric force acts without the objects being in contact.[5]

History

Electric effects have been known for a very long time. The ancient Greek philosopher Thales of Miletus (about 624–546 BCE) recorded that when amber, a hard fossilised tree resin, was rubbed hard with fur, the fur and the amber were attracted to each other.[6] The American physicist and statesman Benjamin Franklin[7] suggested calling an excess of "electrical fluid" positive electricity and a shortage of it negative electricity. With small changes, his idea is the model still used today.[3]

Unit and the elementary charge

Charge is measured in coulombs (symbol C), named after the French physicist Charles-Augustin de Coulomb (1736–1806).[8] Charge is quantised: it comes only in separate amounts, and there is a smallest possible amount.[9] This smallest amount is called the elementary charge, e. Its value is exactly 1.602 176 634 × 10−19 C.[10] The value is fixed exactly because the International System of Units uses it to define the ampere, the unit of electric current.[11] No free particle can have less charge than this, so the charge on any object is a whole-number multiple of it.[12]

Conservation of charge

Charge is conserved. It can move from place to place and from one object to another, but the total charge of the universe stays the same.[13]

Charge in atoms

The electron is the particle that carries the basic unit of negative charge.[14] The positive charge in an atom is in its nucleus, which Ernest Rutherford found was made of small, heavy particles that he named protons.[15] Atoms are normally electrically neutral: they carry equal amounts of positive and negative charge, so their total charge is zero.[16] Everyday objects become charged when electrons are added to them or taken away from them.[17]

References

  1. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. A charge is not a particle; rather, it is a property of a particle.
  2. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. This suggested there were two types of an electric property; this property eventually came to be called electric charge .
  3. ↑ 3.0 3.1 Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. He further suggested that an excess of what he called this "electrical fluid" be called "positive electricity" and the deficiency of it be called "negative electricity." His suggestion, with some minor modifications, is the model we use today.
  4. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. These forces are repulsive when the same type of charge exists on two interacting objects and attractive when the charges are of opposite types.
  5. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. The most peculiar aspect of this new force is that it does not require physical contact between the two objects in order to cause an acceleration.
  6. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. The ancient Greek philosopher Thales of Miletus (624–546 BCE) recorded that when amber (a hard, translucent, fossilized resin from extinct trees) was vigorously rubbed with a piece of fur, a force was created that caused the fur and the amber to be attracted to each other
  7. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. The American physicist and statesman Benjamin Franklin found that he could concentrate charge in a
  8. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. The SI unit of electric charge is the coulomb (C), after the French physicist Charles-Augustin de Coulomb (1736–1806).
  9. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. Charge is quantized. This means that electric charge comes in discrete amounts, and there is a smallest possible amount of charge that an object can have.
  10. ↑ "CODATA Value: elementary charge". The NIST Reference on Constants, Units, and Uncertainty. National Institute of Standards and Technology. Retrieved 18 October 2026. elementary charge Numerical value 1.602 176 634 x 10 -19 C Standard uncertainty (exact)
  11. ↑ "SI base unit: ampere (A)". Bureau International des Poids et Mesures. Retrieved 18 October 2026. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 x 10 –19 when expressed in the unit C, which is equal to A s
  12. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. No free particle can have less charge than this, and, therefore, the charge on any object—the charge on all objects—must be an integer multiple of this amount.
  13. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. Charge is conserved. Charge be transferred from place to place, from one object to another, but the net charge (sum of all the charges) of the universe is constant.
  14. ↑ "18.1 Electrical Charges, Conservation of Charge, and Transfer of Charge". Physics. OpenStax. 2020. Retrieved 18 October 2026. science had in fact discovered the particle that carries the fundamental unit of negative electrical charge. We now know this particle as the electron .
  15. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. Rutherford concluded that the nucleus was constructed of small, massive particles that he named proton s .
  16. ↑ "18.1 Electrical Charges, Conservation of Charge, and Transfer of Charge". Physics. OpenStax. 2020. Retrieved 18 October 2026. Atoms, however, were known to be electrically neutral, which means that they carry the same amount of positive and negative charge, so their net charge is zero.
  17. ↑ Ling, Samuel J.; Sanny, Jeff; Moebs, William (2016). "5.1 Electric Charge". University Physics Volume 2. OpenStax. Retrieved 18 October 2026. All macroscopic, charged objects have charge because electrons have either been added or taken away from them, resulting in a net charge.
Retrieved from "https://tilcayo.cat/w/index.php?title=Electric_charge&oldid=162708"