Question

A tungsten wire has a radius of 0.077 mm and is heated from 20.0 to 1205 °C. The temperature coefficient of resistivity is α = 4.5 10-3 (C°)−1. When 110 V is applied across the ends of the hot wire, a current of 1.3 A is produced. How long is the wire? Neglect any effects due to thermal expansion of the wire.

Answer 1

14380 m

Answer 2

4.44 m