In body centered cubic arrangement the spheres are touching along the leading diagonal of the cube as shown in the In ∆ABC,
AC2 = AB2 + BC2
∴ Volume of the sphere with radius ‘r’
Number of spheres belong to a unit cell in bee arrangement is equal to two and hence the total volume of all spheres
i.e., 68% of the available volume is occupied.The available space is used more efficiently than in simple cubic packing
