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zorro
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Homework Statement
A wire has a resistance of 2 ohm at 25 C and 2.5 ohm at 100 C . Find the temperature coefficient of resistance of the wire.
The Attempt at a Solution
This question is a very easy one, but I had a doubt -
R=Ro(1 + αθ)
Here θ is the change in temperature.
I proceed in 2 ways:
1) We can take Ro = 2 ohm at 25 C so that the equation becomes
2.5 = 2 [1 + α(100-25)]
On solving, α=3.33 x 10-3
2) Take Ro as the resistance at 0 C
2 = Ro(1 + 25α)
2.5 = Ro(1 + 100α)
On solving, α = 3.64 x 10-3
Which one is correct and why?