184_notes:charge_and_matter

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184_notes:charge_and_matter [2021/01/25 00:02] – bartonmo184_notes:charge_and_matter [2021/01/25 00:06] (current) – bartonmo
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 === Conductors === === Conductors ===
  
-//**A conductor is an object or material where charged particles can move easily through the material.**// In some conductors (like salt water), there are charged ions ($\text{Na}^+$ and $\text{Cl}^-$) that can travel relatively freely through the material (water). In other conductors, like metals, the inner electrons of every atom are tightly bound to the nucleus, but the outer electrons (or [[https://en.wikipedia.org/wiki/Valence_electron|valence electrons]]) of the atom are much easier to remove. When you have lot of metal atoms together, generally one electron from each atom can leave the atom and join a "sea" of electrons that are free to move through the metal. These electrons are not completely free - it is very difficult to remove these electrons from the metal - but they are relatively free to move within the piece of metal. This is how we model the metal as a conductor - a mobile electron sea. Common conductors include: salt water, copper, iron, aluminum, gold, etc.  +**A conductor is an object or material where charged particles can move easily through the material.** In some conductors (like salt water), there are charged ions ($\text{Na}^+$ and $\text{Cl}^-$) that can travel relatively freely through the material (water). In other conductors, like metals, the inner electrons of every atom are tightly bound to the nucleus, but the outer electrons (or [[https://en.wikipedia.org/wiki/Valence_electron|valence electrons]]) of the atom are much easier to remove. When you have lot of metal atoms together, generally one electron from each atom can leave the atom and join a "sea" of electrons that are free to move through the metal. These electrons are not completely free - it is very difficult to remove these electrons from the metal - but they are relatively free to move within the piece of metal. This is how we model the metal as a conductor - a mobile electron sea. Common conductors include: salt water, copper, iron, aluminum, gold, etc.  
  
 [{{  184_notes:conductorneg.png?150|Charge distribution in a conductor from a negative charge}}] [{{  184_notes:conductorneg.png?150|Charge distribution in a conductor from a negative charge}}]
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 When you put a positive charge next to a conductor (shown in the figure to the left), the electrons in the electron sea are attracted to the surface of the metal closest to the positive charge. This leaves the opposite surface with a positive charge because those atoms now look like they are missing an electron. Since the positive charges are much further away from the positive charge than the negative charges, the attraction from the conductor is much stronger than the repulsion. This means that the positive charge is strongly attracted to the metal even though the metal is overall neutral.  When you put a positive charge next to a conductor (shown in the figure to the left), the electrons in the electron sea are attracted to the surface of the metal closest to the positive charge. This leaves the opposite surface with a positive charge because those atoms now look like they are missing an electron. Since the positive charges are much further away from the positive charge than the negative charges, the attraction from the conductor is much stronger than the repulsion. This means that the positive charge is strongly attracted to the metal even though the metal is overall neutral. 
  
-**Again, the electrons are what moves in both cases.**+//Again, the electrons are what moves in both cases.//
  
 You might have experienced this effect when you were working with the tape challenge in the first class. Your body is mostly composed of salt water, which is a very good conductor. No matter what kind of charge was on your tape, you may have observed that it was always attracted to your hand, sometimes more than it was to the other piece of tape. This microscopic model of conductors would explain why the tape was always attracted to your hand. You might have experienced this effect when you were working with the tape challenge in the first class. Your body is mostly composed of salt water, which is a very good conductor. No matter what kind of charge was on your tape, you may have observed that it was always attracted to your hand, sometimes more than it was to the other piece of tape. This microscopic model of conductors would explain why the tape was always attracted to your hand.
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  • Last modified: 2021/01/25 00:02
  • by bartonmo