A steel wire of length 'l' and radius of cross–section ‘r’ is stretched horizontally between two rigid supports attached at its ends. A load Mg suspended from its midpoint produces a depression of x well within elastic limit of the material of the wire. The Young’s modulus of the material is
(1) \(\frac{Mgl^2}{8\pi r^2x^2}\)
(2) \(\frac{Mgl^4}{8\pi r^2 x^3}\)
(3) \(\frac{Mgl^3}{8\pi r^2 x^3}\)
(4) \(\frac{Mgl}{8\pi r x^2}\)