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| 184_notes:charge [2021/01/20 15:36] – [Electric Interaction] bartonmo | 184_notes:charge [2021/01/24 23:42] (current) – bartonmo |
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| Charge is one of the basic properties of matter. Just like how an object has a mass, an object also has a charge. | Charge is one of the basic properties of matter. Just like how an object has a mass, an object also has a charge. |
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| There are two types of [[https://en.wikipedia.org/wiki/Electric_charge|electric charge]] - positive and negative - that interact in very specific ways. A positive charge will repel another positive charge and a negative charge will repel another negative charge ("likes repel" rule). On the other hand, a positive charge will attract a negative charge and vice versa ("opposites attract" rule). We also know that more charge or a smaller distance means a stronger interaction, which you may have observed from rubbing a balloon on your hair or sweater. | There are two types of [[https://en.wikipedia.org/wiki/Electric_charge|electric charge]] - positive and negative - that interact in very specific ways. //A positive charge will repel another positive charge and a negative charge will repel another negative charge// ("likes repel" rule). On the other hand, //a positive charge will attract a negative charge and vice versa// ("opposites attract" rule). We also know that more charge or a smaller distance means a stronger interaction, which you may have observed from rubbing a balloon on your hair or sweater. |
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| While these rules may seem relatively simple, they are extremely powerful in describing how charges interact with one another, and you can use these rules to check your mathematical solution or reason conceptually about a problem. For example, if you only have two positive charges, but your math says they are moving toward each other, then you know that you have missed a negative sign in your equations. Or if you double the charge on your object, you know that you should see a stronger interaction. | While these rules may seem relatively simple, they are extremely powerful in describing how charges interact with one another, and you can use these rules to check your mathematical solution or reason conceptually about a problem. For example, if you only have two positive charges, but your math says they are moving toward each other, then you know that you have missed a negative sign in your equations. Or if you double the charge on your object, you know that you should see a stronger interaction. |
| ==== Conservation of Charge ==== | ==== Conservation of Charge ==== |
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| In addition to the [[183_notes:fundamental_principles|3 fundamental principles]] (conservation of momentum, energy, and angular momentum) you learned about in mechanics, there is a fourth fundamental principle, which is important to electromagnetic situations: [[https://en.wikipedia.org/wiki/Charge_conservation|conservation of charge]]. This principle says that the amount of charge in a system should always be constant (or conserved) as long as there is no transfer of charge to/from the surroundings. (This is another reason why [[184_notes:defining_a_system|defining your system]] is an important choice). | In addition to the [[183_notes:fundamental_principles|3 fundamental principles]] (conservation of momentum, energy, and angular momentum) you learned about in mechanics, there is a fourth fundamental principle, which is important to electromagnetic situations: [[https://en.wikipedia.org/wiki/Charge_conservation|conservation of charge]]. **This principle says that the amount of charge in a system should always be constant (or conserved) as long as there is no transfer of charge to/from the surroundings.** (This is another reason why [[184_notes:defining_a_system|defining your system]] is an important choice). |
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| In general, we can always account for all the charge in every observation we make and experiment we conduct (either in the system or moving across the system boundary). | In general, we can always account for all the charge in every observation we make and experiment we conduct (either in the system or moving across the system boundary). |