The de Broglie wavelengths of a proton and an α particle are λ and 2 λ respectively. The ratio of the velocities of proton and α particle will be:

The de Broglie wavelengths of a proton and an $\displaystyle \alpha$ particle are $\displaystyle \lambda$ and $\displaystyle 2 \lambda$ respectively. The ratio of the velocities of proton and $\displaystyle \alpha$ particle will be :