An Iron rod and a Copper rod lies side by side, as the temperature is changed, the difference in the length of the rods remains constant value of 10 cm. The lengths of Iron and Copper rods at zero degree centigrade shall be ---------- . (coefficient of Linear expansion of lron = $$1.1 \times 10^{-5}$$ per degree centigrade and coefficient of Linear expansion of
$$Cu = 1.7 \times 10^{-5}$$ per degree centigrade)