# Uncertainity in velocity

1. Apr 14, 2013

### darkfall

If the uncertainity in position is equal to de broglies wavelength ..den is the uncertainity in velocity equal to the velocity itself????
If yes how???

2. Apr 14, 2013

### Staff: Mentor

$\displaystyle \Delta x \Delta p \geq \frac{\hbar}{2}$. Let $\displaystyle \Delta x = \lambda = \frac{h}{p}$, then $\displaystyle \Delta p \geq \frac{\hbar}{2 \Delta x} = \frac{\hbar p}{2 h} = \frac{p}{4\pi}$.
If the motion is non-relativistic, p=mv and $\displaystyle \Delta v \geq \frac{v}{4\pi}$.
Note that this is a lower limit on the uncertainty.

3. Apr 14, 2013

### darkfall

So its v/(4*pi) ??

4. Apr 14, 2013

### darkfall

All rite...thanks