Question

(a) Crystalline solids are ‘anisotropic’. What is ‘anisotropy’?

(b) Copper crystals have fee unit cells.

(i) Compute the number of atoms per unit cell of copper crystals.

(ii) Calculate the mass of a unit cell of copper crystals. (Atomic mass of copper = 63.54 u)

Answer 1

(a) Anisotropy means physical properties shows different values along different directions, eg. refrative index electrical resistance,

(b) i) Face centred cubic unit cell (fee) – It contains atoms at all the corners and at the centre of all the faces of the cube.

8 corners x \(\frac{1}{8}\) per corner atom