Q 11-10-010NEETJEE MainEAMCET 1983 (Engineering)Easy
A metal rod having a linear coefficient of expansion $2 \times 10^{-5}\ °\text{C}^{-1}$ has a length of $1$ m at $25°$C. The temperature at which it is shortened by $1$ mm is
Answer: (C) $-25°$C
$$\Delta T = \frac{\Delta L}{L\alpha} = \frac{-10^{-3}}{1 \times 2 \times 10^{-5}} = -50°\text{C}$$
New temperature $= 25 - 50 = -25°$C.
Solution by Sreeraj P, M.Sc Physics