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Question: Answered & Verified by Expert
If the kinetic energy of a free electron doubles, it's de-Broglie wavelength changes by the factor
PhysicsDual Nature of MatterJEE Main
Options:
  • A 2
  • B $\frac{1}{2}$
  • C $\sqrt{2}$
  • D $\frac{1}{\sqrt{2}}$
Solution:
2233 Upvotes Verified Answer
The correct answer is: $\frac{1}{\sqrt{2}}$
de-Broglie wavelength,
$$
\begin{array}{l}
\lambda=\frac{\mathrm{h}}{\mathrm{p}}=\frac{\mathrm{h}}{\sqrt{2 \cdot \mathrm{m} \cdot(\mathrm{K} \cdot \mathrm{E})}} \\
\therefore \lambda \propto \frac{1}{\sqrt{\mathrm{K} \cdot \mathrm{E}}}
\end{array}
$$
If $\mathrm{K} . \mathrm{E}$ is doubled, then de-Broglie wavelength becomes $\frac{\lambda}{\sqrt{2}}$

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