The kinetic Energy of an electron having de Broglie wavelength triple, then the de Broglie wavelength associated with it becomes:

\(\frac{λ}{3}\) \(λ\sqrt{3}\) \(\frac{λ}{\sqrt{3}}\) 3λ

\(\frac{λ}{\sqrt{3}}\)

$ \lambda = \frac{h}{mv} = \frac{h}{\sqrt{2mE}} $ $\lambda \propto \frac{1}{\sqrt E}$ $ \lambda \text{ will become }\frac{1}{\sqrt 3 } \text{ times when E is increased to 3 times.}$