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184_notes:dist_charges [2020/08/20 16:03] – dmcpadden | 184_notes:dist_charges [2021/02/13 19:17] – bartonmo | ||
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In the [[184_notes: | In the [[184_notes: | ||
- | === Conducting Sphere of Charge === | + | ==== Conducting Sphere of Charge |
[{{ 184_notes: | [{{ 184_notes: | ||
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This is actually the primary idea behind shielding sensitive electronics (also referred to as a [[https:// | This is actually the primary idea behind shielding sensitive electronics (also referred to as a [[https:// | ||
- | === Insulating Sphere of Charge === | + | ==== Insulating Sphere of Charge |
[{{ 184_notes: | [{{ 184_notes: | ||
If instead we have an insulating, plastic sphere (rather than a metal, conducting one), we would see a very different charge distribution. In an insulator, excess charges cannot move freely and are stuck where they were placed. Thus, if we place a collection of electrons inside the ball, they will stay distributed through the volume of the sphere rather moving to the surface. For the purposes of our class, we will //__assume that any charge on an insulator will be evenly distributed__// | If instead we have an insulating, plastic sphere (rather than a metal, conducting one), we would see a very different charge distribution. In an insulator, excess charges cannot move freely and are stuck where they were placed. Thus, if we place a collection of electrons inside the ball, they will stay distributed through the volume of the sphere rather moving to the surface. For the purposes of our class, we will //__assume that any charge on an insulator will be evenly distributed__// | ||
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Another common example that we will frequently talk about is the idea of a charged cylinder. This will become particularly relevant when we start talking about wires in circuits next week. For now, we'll talk about the shape of the electric field for a conducting and an insulating cylinder of charge. | Another common example that we will frequently talk about is the idea of a charged cylinder. This will become particularly relevant when we start talking about wires in circuits next week. For now, we'll talk about the shape of the electric field for a conducting and an insulating cylinder of charge. | ||
- | === Conducting Cylinder of Charge === | + | ==== Conducting Cylinder of Charge |
Much like what happened with the metal sphere, if we place an excess charge - let's say it's positive this time - on a metal cylinder (like a wire), those charges will spread out as far as they possibly can from one another (" | Much like what happened with the metal sphere, if we place an excess charge - let's say it's positive this time - on a metal cylinder (like a wire), those charges will spread out as far as they possibly can from one another (" | ||
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- | === Insulating Cylinder of Charge === | + | ==== Insulating Cylinder of Charge |
[{{ 184_notes: | [{{ 184_notes: | ||
- | For an insulating cylinder (like a plastic pipe) if we add excess charges, those will stay in place (as charges are not free to move in an insulator). We will again make the assumption in these cases of __//a uniform charge | + | For an insulating cylinder (like a plastic pipe) if we add excess charges, those will stay in place (as charges are not free to move in an insulator). We will again // |
Just like with the sphere, if we are outside the cylinder, the electric field will look the same as if the cylinder were a conductor (as long as it has the same amount of charge). Namely that it points radially away from the positively charged cylinder, expect near the ends of the cylinder. | Just like with the sphere, if we are outside the cylinder, the electric field will look the same as if the cylinder were a conductor (as long as it has the same amount of charge). Namely that it points radially away from the positively charged cylinder, expect near the ends of the cylinder. |