II. Free Response (16 points) Show your work neatly and completely. Do not forget units. A. (2 points) An 8-gauge wire with cross-sectional area of 8.35 mm?, has 6 x 10 electrons flow past any point during a 3 second interval. What is the current density J? 8 x 8.35 2 3 ( 6x(020 ) 2. Intermittent windshield wipers are driven by an RC circuit. Once the voltage across the capacitor reaches 10 V, the wiper motor is energized and discharges the capacitor (this is one complete sweep of the windshield wipers). The capacitor is 15 mF and the resistor is variable with a rang of 0 to 2 k$2 (controlled by the driver). A) (2 points) If the driver sets the RC time constant to 0.5 ms, what is the variable resistor set to? RZ C = 10 ME =V = 12.0 V range clerks Vout B) (4 points) What value should the diver set the variable resistance to, so that the wiper has a period of 20 seconds