Two rods one of aluminium and other made of steel having initial length L1 and L2 are connected together to form a single rod of length L1+L2 . The coefficient of linear expansion for aluminium and steel are ALPHA A and ALPHA S respectively. If the length of each road increases by the same amount when their temperature are raised by T degree celsius, the what is the ratio between L1/ ( L1 + L2 ) ?