Differences
This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision Next revisionBoth sides next revision | ||
184_notes:q_in_wires [2020/08/23 19:20] – dmcpadden | 184_notes:q_in_wires [2021/02/18 20:14] – bartonmo | ||
---|---|---|---|
Line 14: | Line 14: | ||
We will start with the simplest circuit possible: a battery connected by a conducting wire (shown to the right). If we //__assume the battery is a mechanical battery__//, | We will start with the simplest circuit possible: a battery connected by a conducting wire (shown to the right). If we //__assume the battery is a mechanical battery__//, | ||
- | If the electrons are moving, there has to be some sort of force that is making those charges move. From what we talked about before, we know we can write this force on the electron in terms of the electron charge and the electric field it is in: | + | If the electrons are moving, there has to be some sort of force that is making those charges move. [[184_notes: |
$$\vec{F}_{e^-}=q_{e^-}\vec{E}$$ | $$\vec{F}_{e^-}=q_{e^-}\vec{E}$$ | ||
Line 21: | Line 21: | ||
[{{ 184_notes: | [{{ 184_notes: | ||
- | === Hypothesis 1 - Electric field comes from the battery alone === | + | ==== Hypothesis 1 - Electric field comes from the battery alone ==== |
If this were true, the electric field at Point 1 in the wire would point to left given that it is near the positive plate. Likewise, the electric field at Point 2 would also point to the left, given that it is near the negative plate. At Point 3, we would expect the electric field to be point to the right because it is between the positive and negative plates, though it would be smaller because it is further away from the plates. | If this were true, the electric field at Point 1 in the wire would point to left given that it is near the positive plate. Likewise, the electric field at Point 2 would also point to the left, given that it is near the negative plate. At Point 3, we would expect the electric field to be point to the right because it is between the positive and negative plates, though it would be smaller because it is further away from the plates. | ||
Line 32: | Line 32: | ||
This tells us that while the battery certainly contributes to the electric field in the wire, **there must be something else that is adding to the electric field in the wire**. | This tells us that while the battery certainly contributes to the electric field in the wire, **there must be something else that is adding to the electric field in the wire**. | ||
- | === Hypothesis 2 - There are stationary charges on the surface of the wires === | + | ==== Hypothesis 2 - There are stationary charges on the surface of the wires ==== |
[{{ 184_notes: | [{{ 184_notes: | ||
Line 41: | Line 41: | ||
- | === Electric field in the wire follows the surface charge gradient === | + | ==== Electric field in the wire follows the surface charge gradient |
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: | 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: |