Question

At 20°C, a length of copper wire has a resistance of 10.0 Ω What is its resistance when the wire is heated to 65°C? Let α = 0.004 at 20°C. Show all work and include units of measure.

Answer 1

Answer:

R = 11.8 ohms

Explanation:

Formula

R = R_ref[1 + a(T - T_ref)]

Givens

• R_ref = 10 ohms
• T_ref = 20oC
• T = 65oC
• a = 0.004
• R = resistance at 65oC = ???

Solution

R = 10*[1 + 0.004(65 - 20)]

R = 10*[1 + 0.004(45)]

R = 10*[1 + 0.18]

R = 10*(1.18)

R = 11.8 ohms

Be sure you understand not to add the 1 and 0.004 together. You don't get 1.004 at any point of the solution. If you do, you won't know what to do (exactly) with the 45.