Q 12-11-086JEE MainJEE Main 2023 (25 Jan, Shift 1)Easy
Electron beam used in an electron microscope, when accelerated by a voltage of $20\ \text{kV}$ has a de-Broglie wavelength of $\lambda_0$. If the voltage is increased to $40\ \text{kV}$ then the de-Broglie wavelength associated with the electron beam would be
Answer: (D) $\dfrac{\lambda_0}{\sqrt2}$
$\lambda\propto\dfrac1{\sqrt V}$; doubling $V$ gives $\dfrac{\lambda_0}{\sqrt2}$.
Solution by Sreeraj P, M.Sc Physics