1) The voltage in typical household wiring is 120 V. How much current does a 100 W lightbulb draw? What's the bulb's resistance under these conditions? The filament in the lightbulb has a diameter of 0.050 mm.
i) What is the current density in the filament?
ii) Compare it with the current density in a 12-gauge wire (diameter 2.1 mm) supplying current to the lightbulb.
2) Find the capacitance of a parallel-plate capacitor consisting of circular plates 34 cm in radius separated by 2.0 mm.
C=?pF