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| 184_notes:examples:week6_charges_circuit [2018/06/11 19:07] – curdemma | 184_notes:examples:week6_charges_circuit [2021/06/08 00:41] (current) – schram45 | ||
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| On the circuit shown below, draw how you would expect charge to distribute on the surface of the wire near the bends in the circuit. | On the circuit shown below, draw how you would expect charge to distribute on the surface of the wire near the bends in the circuit. | ||
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| ===Facts=== | ===Facts=== | ||
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| * The mobile charge carriers are positive. | * The mobile charge carriers are positive. | ||
| It doesn' | It doesn' | ||
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| + | We will also assume that we have a perfect battery in this case to drive a steady current and provide excess charges to be distributed on the wire. | ||
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| What would have happened if we did not place these charges here? Conventional current would follow the electric field. An electric field vector near the bend would point left, and instead of following the wire, positive charge would build up along the outer surface of the bend (the wider part of the bend) in the wire. Charge would continue to build up until we reach a point where an electric field vector near the bend points down! See below for a representation of how the surface charges near the bends in the wire would look. The electric field (and direction of conventional current) is shown with arrows. | What would have happened if we did not place these charges here? Conventional current would follow the electric field. An electric field vector near the bend would point left, and instead of following the wire, positive charge would build up along the outer surface of the bend (the wider part of the bend) in the wire. Charge would continue to build up until we reach a point where an electric field vector near the bend points down! See below for a representation of how the surface charges near the bends in the wire would look. The electric field (and direction of conventional current) is shown with arrows. | ||
| - | {{ 184_notes: | + | [{{ 184_notes: |
| Notice that as you traverse the length of the wire, the surface charges become less positive and more negative, and eventually start to accumulate on the tighter part of the bend. We require each bend to be more negative than the previous one, so that the electric field on the straight parts of the wire points in the desired direction. And we start to draw the bends with negative charge on the tighter part, because all we need is for the wider part of the bend to be more positive than the tighter part. When drawing positive charge, it will be on the wider part. When drawing negative charge, it will be on the tighter part. | Notice that as you traverse the length of the wire, the surface charges become less positive and more negative, and eventually start to accumulate on the tighter part of the bend. We require each bend to be more negative than the previous one, so that the electric field on the straight parts of the wire points in the desired direction. And we start to draw the bends with negative charge on the tighter part, because all we need is for the wider part of the bend to be more positive than the tighter part. When drawing positive charge, it will be on the wider part. When drawing negative charge, it will be on the tighter part. | ||