A conductor has a resistivity of \( 4 \times 10^{-8} \, \Omega \text{m} \) at \( 20^\circ \text{C} \) and a temperature
**Temperature dependence** of resistance R_t = R₀[1+α(T-T₀)], α temperature coefficient (per °C), R₀ resistance at T₀ (Ω). For metals α positive ≈10⁻³ /°C, resistance increases with temperature because τ decreases due to increased phonon scattering, n nearly constant. Use: rho_t = rho₀ [1 + α (T - T₀)] . Given: rho₀ = 4 × 10⁻⁸ Ω m , α = 4 × 10⁻³ °C⁻¹ , T = 60° C , T₀ = 20° C . Substitute: rho_t = 4 × 10⁻⁸ [1 + 4 × 10⁻³ (60 - 20)] . Calculate: rho_t = 4 × 10⁻⁸ [1 + 0.16] = 4 × 10⁻⁸ × 1.16
Ref: NCERT > Physics Book > Current Electricity > Temperature Dependence of Resistance and Resistivity