Question

Copper has face-centred cubic (fcc) lattice with interatomic spacing equal to $2.54\mathring{A}$ . The value of lattice constant for this lattice is

• A. $1.27\mathring{A}$
• B. $5.08\mathring{A}$
• C. $2.54\mathring{A}$
• D. $3.59\mathring{A}$

Answer 1

Answer: (D)

Interatomic spacing for fcc lattice
$r={\left[{\left(\frac{a}{2}\right)}^2+{\left(\frac{a}{2}\right)}^2+(0{)}^2\right]}^{1/2}=\frac{a}{\sqrt{2}}$
a being lattice constant.
$\therefore a=\sqrt{2}r=\sqrt{2}\times 2.54=3.59\mathring{A}$