Differences

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--- 184_notes:q_in_wires [2021/02/23 20:22] – [Hypothesis 1 - Electric field comes from the battery alone] bartonmo
+++ 184_notes:q_in_wires [2021/02/23 20:23] – [Hypothesis 2 - There are stationary charges on the surface of the wires] bartonmo
@@ Line 38: / Line 38: @@
 Because the wire is made of metal, electrons are free to move and any excess charge will move to the surface of the wire. Thus, when connected to the battery, **there are charges on the surface of the wire**, which contribute to the net electric field in the wire (in addition to the field from the battery).
-For example, near the negative end of the mechanical battery, there are negative charges on the surface of the wire. Near the positive end of the mechanical battery, there are positive charges on the surface of the wire. Moving farther from the negative end of the battery will result in less and less negative surface charges, with the same effect as you move farther from the positive end. In the middle, there must be a place where the surface charge is zero (where the surface charge switches from positive to negative). **This creates a __continuous charge gradient__ along the wire - from the positive end of the battery to the negative end of the battery.** When we say a gradient in this context, we mean that the amount of surface charge changes as you move along the wire. An example of the surface charge gradient is shown in the figure below, where the surface starts as large and positive near the positive plate, decreases along the wire, and ends as large and negative near the negative plate.
+For example, near the negative end of the mechanical battery, there are negative charges on the surface of the wire. Near the positive end of the mechanical battery, there are positive charges on the surface of the wire. Moving farther from the negative end of the battery will result in less and less negative surface charges, with the same effect as you move farther from the positive end. In the middle, there must be a place where the surface charge is zero (where the surface charge switches from positive to negative). **This creates a //continuous charge gradient// along the wire - from the positive end of the battery to the negative end of the battery.** When we say a gradient in this context, we mean that the amount of surface charge changes as you move along the wire. An example of the surface charge gradient is shown in the figure below, where the surface starts as large and positive near the positive plate, decreases along the wire, and ends as large and negative near the negative plate.