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### Heisenberg and Wavelength

Posted: Sun Nov 04, 2018 9:05 pm
Hi,

I am just going over the last test, and one of the conceptual questions asked "How does the change in uncertainty in momentum affect the uncertainty in its wavelength?" I answered that there would be no impact because the Heisenberg principle does not relate momentum and wavelength, but it was incorrect. Would someone provide the correct answer?

Thanks

### Re: Heisenberg and Wavelength

Posted: Sun Nov 04, 2018 9:08 pm
This has to do with the equation wavelength=h/p. Since momentum is the denominator in that equation there is an inverse relationship between momentum and wavelength. Therefore if the uncertainty of the momentum increases then the uncertainty of wavelength decreases and vice versa.

### Re: Heisenberg and Wavelength

Posted: Sun Nov 04, 2018 10:06 pm
The question is trying to get us to mention that the more we know about one, the less we know about the other. So, if we know the uncertainty in position is a very specific discrete value, we will know less about the value in the uncertainty of momentum.

### Re: Heisenberg and Wavelength

Posted: Sun Nov 04, 2018 11:53 pm
momentum does affect wavelength, since they have a reciprocal relationship. That is the concept behind de Broglie's equation (wavelength= plank's constant/momentum)

### Re: Heisenberg and Wavelength

Posted: Mon Nov 05, 2018 12:34 am
It does because wavelength is equal to h/momentum. So they are inversely related the higher the momentum the smaller the wavelength and vice versa.

### Re: Heisenberg and Wavelength

Posted: Mon Nov 05, 2018 1:17 am
wavelength=planck's constant/momentum, so wavelength and momentum do affect each other. However, I believe the question is looking for the answer explaining how the less we know about uncertainty in momentum, the less we know about uncertainty in position and vice-versa.

### Re: Heisenberg and Wavelength

Posted: Fri Nov 16, 2018 1:07 pm
Hey guys, new interesting fact... the kilogram is being redefined! https://youtu.be/c_e1wITe_ig

### Re: Heisenberg and Wavelength

Posted: Tue Dec 04, 2018 1:12 am
momentum and wavelength directly affect each other.

### Re: Heisenberg and Wavelength

Posted: Tue Dec 04, 2018 5:38 pm
If a question like this were to come up on the final, I would find an equation where each variable is included and see if there is a way to relate them together that would assist you in answering the question.

### Re: Heisenberg and Wavelength

Posted: Thu Dec 06, 2018 9:18 pm
I wrote something along the lines of they are inversely proportional to one another and that it is impossible to know both momentum and position at the same time and got credit for it. Hope that helps!

### Re: Heisenberg and Wavelength

Posted: Thu Dec 06, 2018 9:42 pm
Because momentum and wavelength are inverses of one another, if you know the precise value for one then you don't know the value of the other. (vice versa) That is why it is named the Heisenburg Uncertainty Principle.

### Re: Heisenberg and Wavelength

Posted: Sun Dec 09, 2018 10:27 am
Because wavelength=planck's constant/momentum, they have an inverse relationship. As momentum increases, wavelength decreases.