The edge lengths of the unit cells in terms of the radius of spheres constituting fcc,bcc and simple cubic unit cell are respectively________ (i) 2√2r, 4r/√3, 2r (ii) 4r/√3, 2√2r, 2r (iii) 2r, 2√2r, 4r/√3 (iv) 2r, 4r/√3, 2√2r
Option 1) In FCC: The atoms at the face diagonals touch each. If a is the edge length of cube and r is the radius of the atom. So, 2a=4r ⇒a=22r In bcc: The atoms at the body diagonal touch each other. So, 3a=4r ⇒a=34r In simple cubic: The atoms at the corners touch each other. So, a=2r
