Physics
posted by Jenny on .
What is the diameter of a 1.00 meter length of tungsten wire whose resistance is 0.32 ohm (electrical resistance)?

The formula for resistance is:
total resistance = (resistivity) * (length)/(area)
filling in from the problem statement:
0.32 ohms = (resistivity) * 1m/(area)
looking up the resistivity for tungsten:
at 20 C
restivity = 5.28 * 10^8 ohms*m
leaving just the area unknown:
0.32 ohm = (5.28 * 10^8)(ohmm) * (1 m)/(area)
Solve for the area. Then, assuming a round wire, find the diameter that gives that area. 
0.2