45. The first Bragg’s maximum of electron diffraction in a nickel crystal
(d = 0.4086 Å) is found to occur at a glancing angle of 65°. The de Broglie
wavelength of the electrons is:
(a) 6.74 Å
(b) 4.74 Å
(c) 2.74 Å
(d) 0.74 Å
46. The first Bragg’s maximum of electron diffraction in a nickel crystal
(d = 0.4086 Å) is found to occur at a glancing angle of 65°. The velocity of
electrons will be:
(a) 9.84 Â 10
6 m/s
(b) 8.84 Â 10
6 m/s
(c) 7.84 Â 10
6 m/s
(d) 6.84 Â 10
6 m/s
47. An electron beam can undergo diffraction by crystal. In order to have its
wavelength equal to 1.54 Å, the potential through which the beam of electrons
should be accelerated is:
(a) 62.6 V
(b) 63.6 V
(c) 64.6 V
(d) 65.6 V
48. Electrons are accelerated to 344 V and are reflected from a crystal. The first
reflection occurs when the glancing angle is 60°. The interplanar spacing of the
crystal is:
(a) 6.38 Å
(b) 4.38 Å
(c) 2.38 Å
(d) 0.38 Å
Answers
1. (a)
2. (d)
3. (b)
4. (c)
5. (a)
6. (b)
7. (d)
8. (c)
9. (a)
10. (b)
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7 Diffraction of Waves and Particles by Crystal