Question

A metal crystallises in b.C.C. Lattice. The percent fraction of edge length not covered by atom is

Answer 1

Edge uncovered by atom = a-2r . Now we know that in bcc 4r = root 3 a . Therfore edge not covered = a ( 2-root3)/ 2

Hence fraction of edge not covered = (2-root3) /2

= (2-1.732)/2 = 0.268/2 = 0.134

Hope you understand !