1) A wire has resistance of 3.1Ω at 300C and 4.5Ω at 1000C . The temperature coefficient of resistance of the wire is A) 0.00120C−1 B) 0.00240C−1 C) 0.00320C−1 D) 0.00640C−1 Answer: Option *Explanation: Given, t1=300C R1=3.1Ω t2=1000C R2=4.5Ω we know that, temperature coefficient of resistance, α=R2−R1R1t2−R2t1=4.5−3.1(3.1)(100)−(4.5×30) = 1.4310−135=1.4175=0.0080C−1