The conductivity of tungsten at room temperature, 1.8 × 107 (A/m2)/(V/m), is significantly smaller than that of copper. At the very high temperature of a glowing light-bulb filament (nearly 3000...

The conductivity of tungsten at room temperature, 1.8 × 107 (A/m2)/(V/m), is significantly smaller than that of copper. At

the very high temperature of a glowing light-bulb filament (nearly 3000 degrees Kelvin), the conductivity of tungsten is 18

times smaller than it is at room temperature. The tungsten filament of a thick-filament bulb has a radius of about 0.015 mm.

Calculate the electric field required to drive 0.20 ampere of current through the glowing bulb and show that it is very large

compared to the field in the connecting copper wires.