Engineering Physics

Solved Problems

1.     Chromium has BCC structure. Its atomic radius is 0.1249 nm. Calculate the free volume/unit cell.

 

(Set-4–May 2007), (Set-4–Sept. 2006)

Sol: Given data are

Atomic radius of chromium, r = 0.1249 nm.

Free volume/unit cell = ?

If ‘a’ is the BCC unit cell edge length, then the relation between ‘a’ and ‘r’ is

Volume of unit cell, V = a³ = (0.28845)³ nm³

                    = 0.024 nm³

Number of atoms in BCC unit cell = 2

Hence volume of atoms in unit cell,

Free volume/unit cell = V – v = 0.00767 nm³

2.     Lithium crystallizes ...