a) When you put on a wool sweater over a cotton shirt, you'll often see a spark. Why does this happen? Use the triboelectric series below to explain exactly what happens to the charge at the microscopic scale. (-) b) Use symmetry to draw the direction of the electric field at points A and B in the diagram below. air hand asbestos glass hair nylon (panty hose) *wool (suit sweater) rayon silk *cotton (T-shirt) paper *acetate * vinylon acryl * vinylidene polyester (car seat) * polyethylene * polyvinyl chloride silicone teflon