The magnitude J of the current density in a certain wire with a circular cross section of radius R = 2.40 mm is given by J = (3.50 108)r2, with J in amperes per square meter and radial distance r in meters. What is the current through the outer section bounded by r = 0.510R and r = R?

Julia would be observing a. static electricity was caused by her sweater rubbing against her shirt and transferring electrons. she didn't touch anything metal, so that would cancel out b.she most likely didn't rub her sweater against her hair either, so that cancels out c.she also didn't scoot across the carpet while trying to take her sweater off, that cancels out d.so that leaves a.a. is correct.