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Q.
The packing efficiency of the two-dimensional square unit cell shown below is
The Solid State
Solution:
Packing efficiency $=\frac{\text{Area covered by particle}}{\text{Total area}}$
Let us assume radius of circle $= r $
Edge length of square $= a$
So, $\frac{2\times \pi r^{2}}{a^{2}} $
$=\frac{2\pi\,r^{2}}{\left(2\sqrt{2}r\right)^{2}}$
$=\frac{\pi}{4}$
$\Rightarrow \frac{\pi}{4} \times 100$
$=78.5\%$
