h-bar [ENDORSED]

$\Delta p \Delta x\geq \frac{h}{4\pi }$

Posts: 35
Joined: Fri Apr 06, 2018 11:02 am

h-bar

In the Heisenberg uncertainty equation, does h-bar basically mean plancks constant divided by 2pi? Will this number always be the same/constant or are there instances where its different?

Chem_Mod
Posts: 18649
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 602 times

Re: h-bar  [ENDORSED]

h bar is always $\frac{h}{2\pi }$

Jacob Samuels 1E
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am

Re: h-bar

Will we need to memorize the value of h-bar on the test next week?

Caroline Crotty 1D
Posts: 32
Joined: Fri Apr 06, 2018 11:02 am

Re: h-bar

Since on Test #1 we are given many formulas we did not need for that test specifically, I think we can assume h bar will not be specifically given. The formula sheet does include the value of Planck's constant and pi so you can easily use that information and your knowledge of h bar to find the value needed.

EllenRenskoff-1C
Posts: 32
Joined: Fri Apr 06, 2018 11:04 am

Re: h-bar

If h-bar is h/ 2*pi, where does the h/ 4*pi come from in the Heisenberg Indeterminancy Function come from?

Josian1A
Posts: 17
Joined: Tue Nov 14, 2017 3:00 am

Re: h-bar

I was also confused between the practicality of using $\frac{h}{4\pi }$ instead of $\frac{h}{2\pi }$ . What is the difference between the two?

Chem_Mod
Posts: 18649
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 602 times

Re: h-bar

h-bar is used because it is a common value for use with the Schroedinger equation. $\frac{h}{4\pi }$ is a derived quantity in the Heisenberg equation, but it is not represented with a special character because it does not show up as commonly in quantum mechanical equations compared to h-bar.

Emma Leshan 1B
Posts: 30
Joined: Fri Apr 06, 2018 11:03 am

Re: h-bar

The Uncertainty Equation stated in the textbook has 1/2 * h-bar, and since h-bar is h/2pi, we use h/4pi.