Slides for a Mini-lecture on Electrostatics

Even in my inquiry-driven SCALE-UP introductory physics class I often give 5 or 10 minute mini-lectures to get the students oriented before they start hands-on experimental work or group problem-solving exercises.  Next week, my class will be starting the difficult journey through the subject of electrostatics – the relationship between electric field and electric potential that many students find daunting in part because calculus plays a featured role.

Given the difficulty of the subject, it is important that I set the right tone in the opening mini-lecture.  In this post, I am going to share the first few slides I will use in Monday’s mini-lecture.

bentley2

bentley1

These images probably require some explanation.  This is a five-month-old Maltese puppy weighing about three pounds and named Bentley.  I can tell you from personal experience that this puppy has way more intelligence per ounce of brain tissue than I do, and that he is much more fun than I am.  Nevertheless, these pictures were taken by his human in their home city (Chicago) today, a day on which the dew point was hovering around 20 degrees.   At this humidity level, the air is a pretty good insulator and excess charge can accumulate on dog hair.  If the dog hair is positively charged, the individual strands of hair feel repulsive forces from the other strands, thus producing the (adorable) look you see here.  It is a nice demonstration of the nature of electric charge and of Coulomb’s Law.

Don’t you think?

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