19. The wavelengths of L a line for copper (Z = 29) is:
(a) 5.84 Å
(b) 6.84 Å
(c) 7.84 Å
(d) 8.84 Å
20. When a crystal is subjected to monochromatic X-ray beam, the first-order
diffraction is observed at an angle of 15°. If the same X-ray beam is used, the
angle for second-order diffraction is:
(a) 61.2°
(b) 51.2°
(c) 41.2°
(d) 31.2°
21. When a crystal is subjected to monochromatic X-ray beam, the first-order
diffraction is observed at an angle of 15°. If the same X-ray beam is used, the
angle for third-order diffraction is:
(a) 51°
(b) 41°
(c) 31°
(d) 21°
22. The lattice parameter of copper (fcc) is 3.61 Å. The first-order (111) plane
appears at an angle of 21.7°. The wavelength of the X-ray used is:
(a) 0.54 Å
(b) 1.54 Å
(c) 2.54 Å
(d) 3.54 Å
23. Nickel (fcc) has the Bragg’s angle for its (220) reflection 38.2°. If the wavelength of the X-ray used is 1.54 Å, the lattice parameter of nickel will be:
(a) 5.52 Å
(b) 4.52 Å
(c) 3.52 Å
(d) 2.52 Å
24. X-rays of wavelength 1:54 ˚
A are used to calculate the spacing between
(200) planes in aluminum. If the first-order Bragg’s angle corresponding to this
reflection is 22.4°, the lattice parameter of aluminum will be:
(a) 1.05 Å
(b) 2.05 Å
(c) 3.05 Å
(d) 4.05 Å
7.4 Other Diffraction Methods
291