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Alternating Current — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current2 Marks
Question
Write briefly the underlying principle used in Davison-Germer experiment to verify wave nature of electrons experimentally. What is the de-Broglie wavelength of an electron with kinetic energy (of).120 ev? Write briefly the underlying principle used in Davison-Germer experiment to verify wave nature of electrons experimentally. What is the de-Broglie wavelength of an electron with kinetic energy (of).120 ev?
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Answer

Diffraction effects are observed for beams of electrons scattered by the crystals.
$\lambda = \frac{1.227 nm}{\sqrt{\text{V}}}$
$\lambda = \frac{1.227nm}{\sqrt{120}}$
Value $ = \lambda= 0.112 \text{ nm}$
Alternate Answer
$\lambda = \frac{\text{h}}{\sqrt{2\text{meV}}}$
$ = \frac{6.63\times10^{-34}}{\sqrt{2\times9.1\times10^{-31}\times1.6\times10^{-19}\times120}}$
$\lambda = 0.112\text{ nm }$.

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