A block of weight 100 N is suspended by copper and steel wires of same cross-sectional area 0.5 cm2 and length $\sqrt 3$ m and 1 m, respectively. Their other ends are fixed on a ceiling as shown in figure. The angles subtended by copper and steel wires with ceiling are 30 $^\circ$ and 60 $^\circ$, respectively. If elongation in copper wire is ($\Delta {l_c}$) and elongation in steel wire is ($\Delta {l_s}$), then the ratio ${{\Delta {l_c}} \over {\Delta {l_s}}}$ is .............. . [Young's modulus for copper and steel are 1 $\times$ 1011 N/m2 and 2 $\times$ 1011 N/m2 respectively.]