Practice question

Given: A copper plate has an area of 0.8 m² at 60° C . What is the decrease in area when cooled to 10° C ? ( α_l = 1.7 × 10⁻⁵K^{-1 ) These values define the system as per NCERT data. Formula: Given: A_0 = 0.8 m², Δ T = 10 - 60 = -50° C, α_l = 1.7 × 10⁻⁵K^{-1. This is standard NCERT relation. Substitution & Calculation: Δ A = A_0 × 2 α_l Δ T = 0.8 × 2 × 1.7 × 10⁻⁵ × (-50) . Δ A = 0.8 × 3.4 × 10⁻⁵ × (-50) = -0.00136 m² (decrease of 0.00136 m² ). Result: The computed value matches expected outcome and confirms correct choice as per NCERT.