MCQ
Consider a rectangular sheet of solid material of length $\ell=9 cm$ and width $d =4 cm$. The coefficient of linear expansion is $\alpha=3.1 \times 10^{-5} K^{-1}$ at room temperature and one atmospheric pressure. The mass of sheet $m =0.1 kg$ and the specific heat capacity $C _{ v }=900 J kg ^{-1} K^{-1}$. If the amount of heat supplied to the material is $8.1 \times 10^2 J$ then change in area of the rectangular sheet is :-
  • $2.0 \times 10^{-6} m^2$
  • B
    $3.0 \times 10^{-7} m^2$
  • C
    $6.0 \times 10^{-7} m^2$
  • D
    $4.0 \times 10^{-7} m^2$

Answer

Correct option: A.
$2.0 \times 10^{-6} m^2$
(A) $2.0 \times 10^{-6} m^2$
$
\begin{array}{l}
\Delta Q=ms \Delta T \\
8.1 \times 10^2=0.1 \times 900 \times \Delta T \\
\Delta A=A_0 2 \alpha \Delta T=2.0 \times 10^{-6} m^2
\end{array}
$

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