How Do You Calculate Temperature Rise in Copper Windings?

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Homework Statement

The copper windings of a motor have a resistance of 5.8ohms at 22degrees when a motor is idle.After runnning for several hours the resistance rises to 6.8ohms. what is the temperture rise of the windings? assume a constant temperture coefficient of a = 5*10^-3

Have i got the right formula for this problem? or have I missed a step? I quite sure my working is correct but the answer definitely is'nt. Please help

Homework Equations

Tii = (1+a*ti)/(Ri/Rii)

The Attempt at a Solution

Tii = 1+5*10^-3*22/(5.8/6.8)

Tii = 1.088/(5.8/6.8)
Tii = 1.28 degrees (2 d.p.)

 

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Have i got the right formula for this problem? or have I missed a step? I quite sure my working is correct but the answer definitely is'nt. Please help

Homework Equations

Tii = (1+a*ti)/(Ri/Rii)

Explain this formula, as it does not look right. What are Tii, ti, Ri, Rii?


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