Physical Science spent time exploring the property of materials to impede the flow of current - electrical resistance. The definition of resistance was examined, Ohm's Law was studied and factors affecting electrical resistance were described. Tomorrow, we will go over last night's homework and you will have time to further practice your math skills for Ohm's Law calculations. Thursday's lab will have students graphically and mathematically investigate ohmic and non-ohmic materials. To prove that I'm not making stuff up when I lecture, here is a table from an wire manufacturer website which lists resistance values for bare copper wire. Note that the resistance is listed per foot and at a specific temperature (resistance increases with length and temperature) and that it decreases sharply with increasing wire diameter. No, I don't know why wire with a higher gauge number has a smaller diameter. It is just one of those mysteries of life...Take time too, to browse around the site and look at resistance values for other types of metal wire. Note that the overall pattern for resistance variation holds for the different metals and alloys, but the individual values for resistance are different for each type of metal. There is other interesting information there, also. Tidbits about thermal conductivity, specific heat, density...all concepts that we have explored and that will make make a return appearance on the MCAS and class final exams.
BTW: a note for all sections. Although I encourage scientific thinking for all endeavors, as we all move towards and through the electricity studies, please make prudent decisions:
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