You have a metallic rectangular plate with a length of l and a width of w at a specific temperature. Study the change in the area of this plate under a change in temperature ΔT while neglecting the effect of all minimal quantities. The coefficient of linear expansion is α.

• A. ΔA = 2 l w Δ T / α
• B. ΔA = 2 Δ T / α l w
• C. ΔA = 2 l w Δ T
• D. ΔA = 2 α l w Δ T

Answer: (D)