184_notes:batteries

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184_notes:batteries [2018/06/11 19:03] – [Chemical Model of a Battery] curdemma184_notes:batteries [2018/09/19 17:57] – dmcpadden
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 ===== Batteries ===== ===== Batteries =====
-While a pair of charged plates is easy to think about on a general level, it becomes surprisingly complicated to model at a microscopic level. As electrons move from one plate to the other, the amount of excess charge on each plate decreases, which means that over time, the "driving force" that is pushing the electrons through the wire is also decreasing. Thus, the flow of electrons (which we will eventually define as the **electron current**) is always changing - starting as a large flow of electrons from one plate to the other and decreasing until the plates are neutral and there is no electron flow between them.+While a pair of charged plates is easy to think about on a general level, it becomes surprisingly complicated to model at a microscopic level. As electrons move from one plate to the other, the amount of excess charge on each plate decreases, which means that over time, the "driving force" that is pushing the electrons through the wire is also decreasing. Thus, the flow of electrons (which we will eventually define as the [[184_notes:defining_current|electron current]]) is always changing - starting as a large flow of electrons from one plate to the other and decreasing until the plates are neutral and there is no electron flow between them.
  
 Rather than dealing with a constantly changing electron current, we are going to start by thinking about a simpler model - one where we //__assume the electron current is constant__// from a battery. (We will return to this idea of charged plates and a changing electron current next week).  Rather than dealing with a constantly changing electron current, we are going to start by thinking about a simpler model - one where we //__assume the electron current is constant__// from a battery. (We will return to this idea of charged plates and a changing electron current next week). 
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 ==== Mechanical Model of a Battery ==== ==== Mechanical Model of a Battery ====
-{{  184_notes:mechanicalbattery.png?200}}+[{{  184_notes:mechanicalbattery.png?200|Mechanical model of a battery}}]
  
 Oftentimes in circuits, we are less concerned with how the electrons in circuits are produced and are more concerned with what happens to the charges after they are produced. This means we will generally simplify our model of the battery to what we call a "mechanical model" of the battery. In this model, the battery consists of two charged plates, one that is positive and one that is negative, with a conveyor belt that pulls the electrons from the positive plate to the negative plate. In this model, //the conveyor belt represents the chemical reaction in the battery that maintains the separation of charge//.  Oftentimes in circuits, we are less concerned with how the electrons in circuits are produced and are more concerned with what happens to the charges after they are produced. This means we will generally simplify our model of the battery to what we call a "mechanical model" of the battery. In this model, the battery consists of two charged plates, one that is positive and one that is negative, with a conveyor belt that pulls the electrons from the positive plate to the negative plate. In this model, //the conveyor belt represents the chemical reaction in the battery that maintains the separation of charge//. 
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 ==== Symbol for a Battery ==== ==== Symbol for a Battery ====
-{{  184_notes:battery.png?200}}+[{{  184_notes:battery.png?200|Abbreviated representation of a battery}}]
 {{184_notes:battery2.png?50  }} {{184_notes:battery2.png?50  }}
 When describing circuits, we will often draw out a symbolic representation (called a circuit diagram) of the circuit elements that we can use to think about what is happening to the charges in the circuit. When representing a battery, we will either draw out the mechanical model of the battery (including the positive plate, negative plate, and conveyor belt) as shown above, or we will draw out a simplified version of the battery including a short line for the negative plate and a long line for the positive plate (where the steady state is assumed without explicitly drawing the conveyor belt). You may also see a physical drawing of a battery drawn out (particularly in textbooks) with the positive and negative sides of the battery explicitly labeled. Any of these representations of a battery will work. When describing circuits, we will often draw out a symbolic representation (called a circuit diagram) of the circuit elements that we can use to think about what is happening to the charges in the circuit. When representing a battery, we will either draw out the mechanical model of the battery (including the positive plate, negative plate, and conveyor belt) as shown above, or we will draw out a simplified version of the battery including a short line for the negative plate and a long line for the positive plate (where the steady state is assumed without explicitly drawing the conveyor belt). You may also see a physical drawing of a battery drawn out (particularly in textbooks) with the positive and negative sides of the battery explicitly labeled. Any of these representations of a battery will work.
  
  • 184_notes/batteries.txt
  • Last modified: 2021/02/16 20:09
  • by bartonmo