Two Aluminium rods and a steel rod of equal cross-sectional area and equal length `l_(0)` are joined rigidly side by side as shown in figure. Initially the rods are at `0^(@)C`. Find the length of the rod at the temperature `theta` if young's modulus of elasticity of the aluminium and steel are `Y_(a)` and `Y_(s)` respectively and coefficient of linear expansion of aluminum and steel are `alpha_(a)` and `alpha_(s)` respectively.
`|{:("Aluminium"),("Steel"),("Aluminium"):}|`