# Heisenberg's uncertainty principle

in heisenbergs uncertainty principle, how do you know when to use hbar, h, h/2 or hbar/2?

thanks

Related Quantum Physics News on Phys.org
G01
Homework Helper
Gold Member
Heisenberg's uncertainty principle is

$$\Delta x \Delta p \geq \frac{\hbar}{2}$$

Sometimes people will drop the factor of 1/2 or leave out the 2 pi and write h instead of hbar.

It all depends on what you're looking for. If you need an exact value for the uncertainty, you should use $\hbar/2$.

If you're only only concerned about getting an order of magnitude estimate, dropping the factor of 2, 2 pi, or both, won't affect anything.