Tungsten melts at TM 3422 degree C by what factor should yo

Tungsten melts at T_M = 3422 degree C, by what factor should you expect the electrical resistance of Tungsten wire to increase by over its room temperature value when the wire is heated to a temperature very close to T_M? (assume that a remams alpha constant)

Solution

Although the resistance of a conductor changes with the size of the conductor (e.g. thicker wires have less resistance to current flow than thinner wires), the resistance of a conductor also changes with changing temperature. This may be expected to happen because, as temperature changes, the dimensions of the conductor will change as it expands or contracts.

However, materials that are classed as CONDUCTORS tend to INCREASE their resistance with an increase in temperature. INSULATORS however are liable to DECREASE their resistance with an increase in temperature. Materials used for practical insulators (glass, plastic etc.) only exhibit a marked drop in their resistance at very high temperatures. They remain good insulators over all temperatures they are likely to encounter in use.