Question

an electron accelerated through 100 V has a de broglie wavelength 'lambda' associated with it. what should be the accelerating potential in order to reduce the wavelength to' lambda/2.'

Answer 1

$$\begin{gathered} Ifweconsider\lambda asdebrogliewavelengththenitisrelatedtothepotentialVbytherelation \\ \lambda =\frac{h\vartheta }{eV} \\ so\frac{{\lambda }_1}{{\lambda }_2}=\frac{V_2}{V_1} \\ Now{\lambda }_2=\frac{{\lambda }_1}{2} \\ So \\ \frac{V_2}{V_1}=2;V_2=200V\left\{ANS\right\} \end{gathered}$$