If the potential difference used to accelerate electrons is increased four times, by what factor does the…

If the potential difference used to accelerate electrons is increased four times, by what factor does the de-Broglie wavelength associated with the electrons change?
  1. Wavelength increased two times
  2. Wavelength decreased to half
  3. Wavelength increased four times
  4. Wavelength remains the same

Solution

$\begin{array}{ll} & \lambda \propto \frac{1}{\sqrt{\mathrm{~V}}} \\ \therefore & \frac{\lambda_2}{\lambda_1}=\sqrt{\frac{\mathrm{V}_1}{\mathrm{~V}_2}} \end{array}$
Given that, $\mathrm{V}_2=4 \mathrm{~V}_1$ $\therefore \quad \lambda_2=\lambda_1 \times \sqrt{\frac{\mathrm{V}_1}{4 \mathrm{~V}_1}}=\frac{\lambda_1}{2}$

Asked in: MHT CET 2024 (10 May Shift 1)

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