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Mechanical Engineering - Engineering Materials - Discussion

Discussion Forum : Engineering Materials - Section 6 (Q.No. 6)
Engineering Materials
6.
In a face centred cubic space lattice, there are
nine atoms out of which eight atoms are located at the corners of the cube and one atom at its centre
fourteen atoms out of which eight atoms are located at the corners of the cube and six atoms at the centres of six faces
seventeen atoms out of which twelve atoms are located at the twelve corners of the hexagonal prism, one atom at the centre of each of the two hexagonal faces and three atoms are symmetrically arranged in the body of the cell
none of the above
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
1 comments Page 1 of 1.
Subhajit said:   9 years ago
14 atoms are associated with the FCC unit cell. But number of atoms in FCC unit cell is known to be 4, because each of 6 face atoms is shared by two unit cells, so in one FCC unit cell there are 6 * 1/6 = 3, and each of eight corner atom is shared by 8 unit cells, so in one unit cell there is 8 * 1/8 = 1 atom.

So total 6 * 1/6 + 8 * 1/8 = 3 + 1 = 4 atoms are there in one FCC unit cell. In this type of calculation obviously hard sphere model is assumed, that is atoms are considered to be the hard sphere.
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