184_notes:q_in_wires

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184_notes:q_in_wires [2021/02/23 20:23] – [Hypothesis 2 - There are stationary charges on the surface of the wires] bartonmo184_notes:q_in_wires [2021/02/23 20:26] – [Electric field in the wire follows the surface charge gradient] bartonmo
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 The electric field around the circuit then follows the charge gradient, pointing from more positive areas of the wire to less positive areas (or from less negative areas to more negative areas). Ultimately, this means that the **electric field follows the wire pointing from the positive end of the battery to the negative**. Remember that because electrons are negative charges, [[184_notes:pc_force|they will move in the direction opposite of the electric field]]. In a circuit then, the electrons that are driven by the mechanical battery follow the wire opposite to the electric field that is set up by the surface charges.  The electric field around the circuit then follows the charge gradient, pointing from more positive areas of the wire to less positive areas (or from less negative areas to more negative areas). Ultimately, this means that the **electric field follows the wire pointing from the positive end of the battery to the negative**. Remember that because electrons are negative charges, [[184_notes:pc_force|they will move in the direction opposite of the electric field]]. In a circuit then, the electrons that are driven by the mechanical battery follow the wire opposite to the electric field that is set up by the surface charges. 
  
-The contributions of the surface charges generate an electric field that adds with the electric field due to the battery (via [[184_notes:superposition|superposition]]). The result //__in steady state__// is that **the surface charges in the wire and the battery's electric field set up a __constant electric field__ along the wire, which pushes the electron current in the opposite direction of the electric field** (from the negative end to the positive end of the battery). Now, when the wire is physically far away from the battery, the electric field due to the battery is small. So often, we just assume __// that the constant electric field in the wire is due (mostly) to the surface charges//__. This is a pretty good assumption anywhere far from the battery (which is pretty much everywhere in macroscopic terms). This might violate your intuition a bit as you expect the field to die off away from the source of charges, but rest assured the electric field is constant through the wire.+The contributions of the surface charges generate an electric field that adds with the electric field due to the battery (via [[184_notes:superposition|superposition]]). The result //__in steady state__// is that **the surface charges in the wire and the battery's electric field set up a //constant electric field// along the wire, which pushes the electron current in the opposite direction of the electric field** (from the negative end to the positive end of the battery). Now, when the wire is physically far away from the battery, the electric field due to the battery is small. So often, we just assume __// that the constant electric field in the wire is due (mostly) to the surface charges//__. This is a pretty good assumption anywhere far from the battery (which is pretty much everywhere in macroscopic terms). This might violate your intuition a bit as you expect the field to die off away from the source of charges, but rest assured the electric field is constant through the wire.
  
 If we consider the surface charge hypothesis, this is much more consistent with what we observe when we connect a wire to a battery: If we consider the surface charge hypothesis, this is much more consistent with what we observe when we connect a wire to a battery:
  • 184_notes/q_in_wires.txt
  • Last modified: 2021/06/08 00:38
  • by schram45