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