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184_notes:examples:week2_conducting_insulating_balls [2017/08/24 22:57] – tallpaul | 184_notes:examples:week2_conducting_insulating_balls [2018/01/22 00:43] – tallpaul | ||
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- | ===== Example: Charged conducting balls vs insulating balls ===== | + | ===== Attempting to Charge Insulators by Induction |
- | Charged conducting balls vs insulating balls | + | In the notes on [[184_notes: |
===Facts=== | ===Facts=== | ||
- | * The Avogadro constant is $N_A = 6.022 \cdot 10^{23} \text{ mol}^{-1}$ | + | * Electrons in an insulator are tightly bound to the nucleus, so the atoms can polarize but charges cannot move freely through an insulator. |
- | * Note: When we write the unit as $\text{ mol}^{-1}$, we mean particles per mole. We could also write this unit as $mol^{-1}=\frac{1}{mol}$. | + | |
- | * All electrons have the same charge, which is $e = -1.602\cdot10^{-19} \text{ C}$. | + | |
- | ===Lacking=== | + | ===Representations=== |
- | * Total Charge | + | * From the notes, we can pull a representation for how we would charge // |
+ | {{ 184_notes: | ||
+ | * We can model the atoms in an insulator as little ovals (like the one below), that show when one side of the atom is more positive or negative than the other side. When ovals are not shown, this will just mean the atoms are not polarized. | ||
+ | {{ 184_notes: | ||
+ | |||
+ | ===Goal=== | ||
+ | * Create an explanation for whether it is possible to charge a pair of insulators using induction. | ||
+ | |||
+ | ====Solution==== | ||
===Approximations & Assumptions=== | ===Approximations & Assumptions=== | ||
- | * None, we have all the information | + | * We will use the same induction process as we did for conductors. |
+ | * The insulators start out neutral, meaning there are no excess electrons on the surface or any unbounded electrons (all electrons have a corresponding positive nuclei). | ||
- | ===Representations=== | ||
- | * The total number of particles $N$ can be found from the number of moles $m$ using the Avogadro constant: $N = m \cdot N_A$. | ||
- | * The total charge $Q$ can be written as the number of particles $N$ times the charge of each particle ($e$, for electrons): $Q=N\cdot e$. | ||
- | ====Solution==== | + | We show the analogous " |
- | yeas | + | |
+ | {{ 184_notes: | ||
+ | |||
+ | The critical difference between conductors and insulators is that electrons can flow from one conductor to the other, but for insulators the electrons are bound to their nuclei. Because of this, the insulators do not charge by induction. |