Question

A certain metal has a resistivity of 1.68 × 10-8 Ω ∙ m. You have a long spool of wire made from this metal. If this wire has a diameter of 0.15 mm, how long should you cut a segment so its resistance will be 15 Ω?

Answer 1

Answer:

15.78 m

Explanation:

Length = resistance×area/resistivity

Resistance = 15 ohms

Area = πd^2/4 = 3.142×(0.15/1000)^2/4 = 1.767375×10^-8 m^2

Resistivity = 1.68 ohm-meter

Length = 15×1.767375×10^-8/1.68×10^-8 = 15.78 m