An alpha particle, a proton and an electron are moving with equal kinetic energy. Which one of these particles has the longest de Broglie wavelength? Give reason.

Explanation

`lamda= (h)/(sqrt(2mE)), lamda prop (1)/(sqrtm)`
`m_(alpha) gt m_(p) gt m_(e )`
`lamda_(e ) gt lamda_(p) gt lamda_(alpha)`
`therefore` electron has longest wavelength, because of smaller mass.