Given,
The area of the silver plate, A=800 m²
The change in the temperature, ΔT=100 °C-15 °C=85 °C=85 K
The area thermal expansion coefficient of silver is α=19×10⁻⁶ K⁻¹
The thermal expansion in the area is given by,
[tex]\Delta A=2\alpha A\times\Delta T[/tex]On substituting the known values,
[tex]\begin{gathered} \Delta A=2\times19\times10^{-6}\times800\times(85) \\ =2.58\text{ m}^2 \end{gathered}[/tex]Thus the increase in the area of the given silver plate is 2.58 m²