A lot of concepts in the lab and there are many new terms just handed to the kids (insulator, conductor, electrons, negative and positive charges). I think that there are good things here but it moves too quickly for a novice. I think it would be better if it would be broken up and cover one new concept at a time (sticky tape = likes repel and opposites attract). I don't know if there are any simulations of triboelectric phenomena or not but I think this might be a good idea before presenting the idea of positive/negative. I guess I would like to know what the reason was historically for those terms why not electric/anti-electric or amber/silk or yellow/white???? Then students can be introduced to the terms conductor/insulator. Josie shared an idea of having the students form a human circle circuit with an "insulator" or a "conductor" so students see the effects and therefore define these themselves. Then I would might have the students expand upon the introductory sticky tape lab to investigate how to remove charges, which is positive/negative, and the difference between induction and polarization.
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Interesting side topic today in the modeling workshop. I love these things. "If a wound up bunny moves up a hill where is the gravitational potential energy stored?"
a. In the bunny b. In the gravitational field of the earth c. In the gravitational field of the bunny d. In the gravitational field of the system The conversation became somewhat sematical (is that a word). One could argue that the bunny stores the energy in the earth's gravitational field. Or could they? If a single mass occupies an otherwise massless universe does it have a gravitational field? Likewise if a positive point charge occupies an otherwise chargeless universe does it have an electric field? Electric field lines help us to conceptualize the electric field and they are defined to begin on a positive charge and end on a negative charge. If a lone positive charge were to have electric field lines emanating from it they would be spherically symmetric. However where are the lines going? They either go somewhere or they don't. If they go somewhere then the somewhere is negative but we just said that there is no other charges in the universe. Hmmm then I guess they go nowhere and they don't come from the charge and therefore we don't even know the charge is positive. In a like manner if there are no other masses in this otherwise massless universe (except for one point mass) then there must not be any gravitational fields associated with the mass and therefore there would be no mass associated with this lone "mass". Hmmmm. So where does General Relativity come in here? There would still have to be some effect of the lone object's mass on space-time. So is there still a gravitational field here? Would there still be an electric field for the lone "charge"? Too many questions . . . too few answers. |
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