The length of an iron bar is 100cm at 20°C. At what temperature will its length increase by 0.01%? [Linear expansivity of iron = 1.2 x 10\(^{-5}\)°C]
A. 48.0°C B. 38.0°C C. 28.3°C D. 23.0°C
Correct Answer: C
Explanation
GIVEN DATA: where ΔL is the increase in length = 0.01
L1 is the initial length = 100 T1 = 20 T2 = ?
α is the linear expansivity of iron = 1.2 x 10\(^{-5}\)°C Formula ΔL = L1αΔT ΔT = \(\frac{ΔL}{L1α}\) ΔT is the change in temperature = T2 - T1 T2 = \(\frac{ΔL}{L1α}\) + T1 T2 = \(\frac{0.01}{100 \times 1.2 x 10^{-5}}\) + 20 T2 = 8.3 + 20 T2 = 28.3
