GATE 2022 PH – Question 62
In an X-Ray diffraction experiment on a solid with FCC structure, five diffraction peaks corresponding to (111), (200), (220), (311) and (222) planes are observed using 1.54 Å X-rays. On using 3 Å X-rays on the same solid, the number of observed peaks will be ________________
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Correct answer: 1
Explanation
The absence of the next FCC peak (400) with the original wavelength bounds the lattice constant below 3.08 angstroms. With wavelength 3, only the (111) reflection can satisfy Bragg diffraction.