The coefficient of expansion of a crystal in one direction (x-axis) is 2.0×10−6 K−1 and that in the other two perpendicular directions (y and z-axes) is 1.6×10−6 K−1,What is the coefficient of cubical expansion of the crystal?
5.2×10−6 K−1
Coefficient of cubical expansion, γ=αx+αy+αz=αx+2ay=2.0×10−6+2×1.6×10−6=5.2×10−6 K−1
Hence, the correct choice is (d).