Common light bulbs have a mental filament made of tungsten and when a current passes through it, it radiates visible light, as well as heat. If initially the filament's resistance is 2.45 ohm (6%) at 20 degrees Celsius and the temperature coefficient of resistivity α is 0.004403/degrees Celsius, what is its resistance at 40 degrees Celsius? And at 60 degree Celsius? (include the uncertainty of the result)

Question

As the filament's temperature increases, does its resistance stay the same, increase or decrease?

Answer 1

It increases with increasing temperature.

http://en.wikipedia.org/wiki/Resistivity