I fthe uncertainty in position of a moving electron is equal to its de Broglie wavelength, prove that its velocity is completely uncertain.

Explanation

Uncertainty in the position of the electron, `Deltax=lamda`.
`lamda=h/lamda =(h)/(Deltax) or, " "Deltax=(h)/(p)`
According to heisenberg's uncertainty principle,
`Deltax*Deltap ge(h)/(4pi)" "or, (h)/(p)*Deltap ge(h)/(4pi) or, (Deltap)/(p)ge(1)/(4pi)`
or, `(mDeltav)/(mv) ge (1)/(4pi) or, Deltav ge (v)/(4pi)`
The uncertainty in velocity is so large that its velocity is uncertain.