Chemistry - Atomic Structure Question with Solution | TestHub

An electron practically at rest in initially accelated through 144 volts. It the has a debroglie wavelength $={\lambda }_1$, it then get retarded through 23 voltes & then has a de-broglie wavelength $={\lambda }_2$, A further retardation through 40 volts changes the wavelength to ${\lambda }_3$ then value of $\frac{72}{77}\times \left(\frac{{\lambda }_1+{\lambda }_3}{{\lambda }_2}\right)$ is equal to?