Answer:
[tex]LD=\dfrac{1}{\sqrt2 \ a}[/tex]
Explanation:
Given that
Unit cell is in FCC
Here given direction is not clear visible so we take direction [101].
We know that linear density(LD) given as
[tex]LD=\dfrac{Number\ of\ atoms\ in\ the\ direction\ vector}{d_{[101]}}[/tex]
So the number of atom will be 1 in direction [101]
In FCC
[tex]a=2\sqrt2 \ r[/tex]
[tex]LD=\dfrac{1}{\sqrt2 \ a}[/tex]
[tex]LD=\dfrac{1}{4r}[/tex]