i) A tungsten filament of 0.100 mm diameter in a light bulb is to encompass a resistance of 0.200 ohms at 20oC. The resistivity of tungsten is around 5.6 x10-8 ohms * m. Determine how long should it be?
ii) A wire is 25.0 m long having a 0.100 mm diameter, and exhibits a resistance of 77.7 ohms at 20oC. Suppose that the temperature coefficients of resistivity, alpha is on the order of 10-3 oC-1. Determine its resistance at 150 oC?