Practice question

Given: A wire has a resistance of 30 Ω at 25° C and 31.5 Ω at 75° C . What is the temperature coefficient of resistivity? These values define the system as per NCERT data. Formula: Use: R_t = R_0 [1 + α (T - T_0)]. This is standard NCERT relation. Substitution & Calculation: Substitute: 31.5 = 30 [1 + α (75 - 25)] . Solve: 31.5 = 30 + 1500α Rightarrow 1500α = 1.5 Rightarrow α = 1.5/1500 = 1.0 × 10⁻³°C^{-1 . Result: The computed value matches expected outcome and confirms correct choice as per NCERT.