A particle A of mass ‘m’ and charge ‘q’ is accelerated by a potential difference of 50 V. Another particle B of mass ‘4m’ and charge ‘q’ is accelerated by a potential difference of 2500 V. The ratio of de-Broglie wavelengths \(\frac{{{{\rm{\lambda }}_{\rm{A}}}}}{{{{\rm{\lambda }}_{\rm{B}}}}}\) is close to