Mumbai university > FE > SEM 1 > Applied Physics 1

Marks: 7M

Year: May 2014

Space lattice-

It is the three dimensional arrangement of points in space.

Basis-

Group of atoms, which get attached to the lattice points is called the basis, hence crystal structure is formed by the combination of lattice & basis.

Given:

$Density (ρ ) = 2.7gm/cc \ \ \ \ i.e. 2.7 × 10^{-3}kg/cc$

$Atomic \ \ distance (a) = 2.86 A^0 \ \ \ \ i.e. 2.86 × 10^{-10}m$

To find: Mass (M) =?

Solution:

As packing fraction is 0.74 it is an FCC structure

$a = 2.86 × 10^{-10}m$

Volume = $a^3$ = $(2.86 ×10^{-10})^3 = 2.34 × 10^{-29}m$

density = Mass/volume

Mass = density × volume

$ = 2.7×10^{-3} × 2.34 × 10^{-29}$

$ = 6.318 × 10^{-32}kg$