Temperature increase due to increase of resistance

[pokie_panda]

Homework Statement

To what value would you have to raise the temperature of a copper wire (originally at 20 deg/C ) to increase its resistance by 14 % ?

The Attempt at a Solution

temp. coeffic of copper = 0.004
delta T = 0.14/0.004

delta T = 35 deg/C

why is this incorrect.

 

[truesearch]

You need to realize that the temp coefficient (0.004/C) means that the resistance of copper Changes by 0.004 x resistance at 0C for each degree change in temperature
So R = Ro(1 + αt) where R = resistance at tC and α = temp coeff of resistance
Have you met this equation?
correction made

 

[pokie_panda]

Yeh I have seen the equation somewhere in the textbook thanks for help