A steel rod and a copper rod

PHYSICS · Single correct · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A steel rod and a copper rod, each

1.0\,\text{m}

long at

20\,^{\circ}\text{C}

, are rigidly joined end to end. The coefficients of linear expansion are

\alpha_{\text{steel}} = 12\times10^{-6}\,\text{K}^{-1}

and

\alpha_{\text{copper}} = 17\times10^{-6}\,\text{K}^{-1}

. At what temperature will the copper rod be

1.5\,\text{mm}

longer than the steel rod? (a)

120\,^{\circ}\text{C}

(b)

320\,^{\circ}\text{C}

(c)

50\,^{\circ}\text{C}

(d)

170\,^{\circ}\text{C}