The energy and momentum of an electron are related to the frequency and wavelength of the associated matter wave by the relations :
` E = h v , p = h/lambda`
But while the value of `lambda` is physically signidficant , the value of v ( and therefore , the value of the phase speed v `lambda` ) has no physical significance . Why ?

Explanation

As `lambda = h/p , p = h/lambda rArr E = hv = (hc)/lambda`
Energy of moving particle `e' = (p^(2))/(2m) = 1/2 ((h/lambda)^(2))/m=1/2 (h^(2))/(lambda^(2)m)`
For the relation of E and p we , note that there is a physical signifivance of ` lambda` but not for frequency v .