Let the Young’s Modulus of steel and copper be Ys and
Yc respectively
Length of steel wire, Ls = 4.7 m
Length of copper wire, Lc = 3.5 m
Area of cross-section of steel wire,
As = 3 × 10-5 m2
Area of cross-section of copper wire,
Ac = 4 × 10-5 m2
Since change in lengths are equal.
∴ ∆Ls = ∆Lc = ∆L.
As the load is same, Fs = Fc = F
We have, Y = (F/A x L/∆L)
= 1.79.
The ratio of Young’s Modulus of steel to that of copper is ≃ 1.8 :1.
