Day 45: Electric Fields

Today, we built upon the computational models for Coulomb’s Law which essentially became electric field vector diagrams. Historically, students have struggled to develop a deep understanding of electric fields. In the past, I used to “cover” electric fields in our first year course. I found that in AP Physics B, students retained little understanding. The past couple of years, I have introduced fields using the recommendations in Knight’s Five Easy Lessons; specifically, page 207-208. I’m impressed by how much discussion and learning can be achieve related to this simple diagram:

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As recommended in the book, I ask students to draw the corresponding electric field vectors at each of the three points. I then point to the middle of one of the vectors and ask them if an electric field exists at that point and, if so, what is its direction. Finally, I ask them to draw force vectors for charges of different signs and magnitudes at the points. This sequence of questions seem to address many of the common misunderstandings regarding electric fields.


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