How can the uncertainty relation be written as such

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Homework Help Overview

The problem involves rewriting the uncertainty relation in the context of quantum mechanics, specifically relating to the variables of wavelength and position. The original poster attempts to manipulate the standard uncertainty relation to derive a specific form involving wavelength.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the transformation of the uncertainty relation and question the steps taken in the manipulation of the equations. There is confusion regarding the treatment of Δh and the implications of substituting variables.

Discussion Status

The discussion is ongoing, with participants providing clarifications and questioning each other's reasoning. Some guidance has been offered regarding the correct interpretation of the uncertainty relation and the manipulation of terms, but no consensus has been reached on the final form of the equation.

Contextual Notes

There appears to be confusion surrounding the definitions and relationships between the variables involved, particularly in the context of the uncertainty principle. Participants are also addressing potential mistakes in the original formulation of the uncertainty relation.

Abdul.119
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Homework Statement


Show that the uncertainty relation can be written as
Δλ Δx >= λ^2 /4π

Homework Equations

The Attempt at a Solution


Ok the uncertainty relation is ΔpΔx >= h/2π , also p = h/λ , so substituting that I have Δh/λ Δx >= h/2π , then divide both sides by h, and multiply both sides by λ^2, so I get Δλ Δx >= λ^2 /2π , which is still not the same as the one given, I don't understand how the 2π becomes 4π
 
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The minimum uncertainty is ##\displaystyle \frac{\hbar}{2}##.
 
Abdul.119 said:
Ok the uncertainty relation is ΔpΔx >= h/2π
Are you sure about that?

Abdul.119 said:
also p = h/λ , so substituting that I have Δh/λ Δx >= h/2π
I don't understand what you are doing here. How can you have Δh?
 
Abdul.119 said:
Δh/λ Δx >= h/2π
I assume you mean Δ(h/λ) Δx, which is hΔ(1/λ) Δx
Abdul.119 said:
multiply both sides by λ^2
But that isn't what you did.
Δ(1/λ) is not the same as 1/Δλ. What does it turn into?
 
Right I had a mistake in the uncertainty relation that's why I was confused. I took care of it now, thank you for the help.
 

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