Step 1: Using Relation for variation of resistance with Temperature
Resistance R varies with Temperature as follows:
R=R0[1+α(T−T0)]
Where, R0 is initial Resistance at Temperature T0
R is initial Resistance at Temperature T
α is the temperature coefficient of resistance.
Step 2: Putting values
Given, T0=27.5oC, R0=2.1Ω, T=100oC, R=2.7Ω
So, Equation (1) ⇒ 2.7Ω=2.1Ω[1+α(100−27.5)oC]
⇒ α=R−R0R0(T−T0)=2.7−2.12.1(100−27.5)=3.9×10−3 oC−1