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# Differences

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activities:guides:vfering 2019/05/30 08:59 | activities:guides:vfering 2019/06/03 13:37 current | ||
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* If you are doing this activity without having had students first create power series expansions for the electrostatic potential due to two charges, students will probably find this portion of the activity very challenging. If they have already done the Discrete Charges activity, or similar activity, students will probably be successful with the $y$ axis case without a lot of assistance because it is very similar to the $y$ axis case for the two $+Q$ point charges. However, the $y$ axis presents a new challenge because the ``something small'' is two terms. It will probably not be obvious for students to let $\epsilon = {2R\over r}\cos\phi' + {R^2\over r^2}$ (see Eq. 17 in the solutions) and suggestions should be given to avoid having them stuck for a long period of time. Once this has been done, students may also have trouble combining terms of the same order. For example the $\epsilon^2$ term results in a third and forth order term in the expansion and students may not realize that to get a valid third order expansion they need to calculate the $\epsilon^3$ term. | * If you are doing this activity without having had students first create power series expansions for the electrostatic potential due to two charges, students will probably find this portion of the activity very challenging. If they have already done the Discrete Charges activity, or similar activity, students will probably be successful with the $y$ axis case without a lot of assistance because it is very similar to the $y$ axis case for the two $+Q$ point charges. However, the $y$ axis presents a new challenge because the ``something small'' is two terms. It will probably not be obvious for students to let $\epsilon = {2R\over r}\cos\phi' + {R^2\over r^2}$ (see Eq. 17 in the solutions) and suggestions should be given to avoid having them stuck for a long period of time. Once this has been done, students may also have trouble combining terms of the same order. For example the $\epsilon^2$ term results in a third and forth order term in the expansion and students may not realize that to get a valid third order expansion they need to calculate the $\epsilon^3$ term. | ||

- | **Notes from 2019** | + | **Notes from 2019** FIXME Everything above this is copied and pasted in the Student Conversations for the Electrostatic potential due to a ring of charge Activity |

* Emphasize that the number of integrals ($\int$) tells us the dimensionality of the source. | * Emphasize that the number of integrals ($\int$) tells us the dimensionality of the source. | ||

* Students well often overgeneralize: | * Students well often overgeneralize: |