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Heisenbergs uncertainity principle for an electron

  • #1
672
0

Homework Statement


The speed of an electron is measured to within an uncertainty of 2e4 m/s. What is the size of the smallest region of space in which the electron can be confined?


Homework Equations


Diracs Constant=ΔxΔp
p=mv

The Attempt at a Solution


what I did was (Diracs Constant)/mv = Δx, (1.054560653e-34)/((9.109e-31)(2e4))=6nm this is this incorrect but I dont understand why?
 

Answers and Replies

  • #2
611
2

Homework Statement


The speed of an electron is measured to within an uncertainty of 2e4 m/s. What is the size of the smallest region of space in which the electron can be confined?


Homework Equations


Diracs Constant=ΔxΔp
p=mv

The Attempt at a Solution


what I did was (Diracs Constant)/mv = Δx, (1.054560653e-34)/((9.109e-31)(2e4))=6nm this is this incorrect but I dont understand why?
Hi,
I am not sure, I may be wrong.
Use Heisenberg uncertainty principle:
[tex]\Delta x \Delta p ≥ \hbar/2.
[/tex]
The given value is not the speed of electron. It is the uncertainty of speed.
Got it?
 
  • #3
1,225
75
Hi. Not value but only order of value has meaning in this situation. Order of nano meter seems fine. What is the 'correct' answer you have got?
 
  • #4
672
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Sweet springs the correct answer is 5.8nm what I get is 6nm I know it's so close but it's not what I'm getting. Rajini given the uncertainty of speed how then would I find speed go the electron so I can find p.
 
  • #5
672
0
Ok I'm starting to think I got the right answer after using wolfram I get 5.78 I am starting to think my calculator has some kind of rounding algorithm
 

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