The de-Broglie wavelength `lamda`

The de-Broglie wavelength lambda

de-Broglie wavelength lambda is

An electron of mass m_(e) and a proton of mass m_(p) are moving with the same speed. The ratio of their de-Broglie wavelength lamda_(e)//lamda_(p) is

A particle A of mass m and initial velocity v collides with a particle of B of mass m/2 which is at rest. The collision is head-on and elastic. The ratio of the de Broglie wavelengths lamda_(A) "to" lamda_(B) after collision is