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### Calculating Uncertainty in Momentum

Posted: Thu Oct 25, 2018 3:07 pm
If you are asked to calculate the uncertainty in momentum, would you normally use the diameter or radius of the atom for the uncertainty in position?

Furthermore, if it is stated that the uncertainty is 1% of the radius 0.05 nm, would the uncertainty in position value equal 0.01*0.05*10^-9?

### Re: Calculating Uncertainty in Momentum

Posted: Thu Oct 25, 2018 3:14 pm
Normally you use the uncertainty in diameter unless the givens in the problem state otherwise as seen in the exercise you mentioned. To answer your second question, yes the uncertainty in position would be exactly as you stated because that's how the problem presents that given. Hope this helped.

### Re: Calculating Uncertainty in Momentum

Posted: Thu Oct 25, 2018 3:22 pm
In calculating uncertainty in momentum, you would normally use the value for diameter.
But in the example you gave, they gave a specific section of the atom wherein the position of an electron could be found. So you would use the given (which is 1% of radius) to calculate the uncertainty in position. So your delta x would be equal to 0.01*0.05*10^-9 as you said.

### Re: Calculating Uncertainty in Momentum

Posted: Fri Oct 26, 2018 12:16 am
use diameter for calculating uncertainty in position (delta x) because the diameter encompasses the whole area that the electron could be located. yes, your calculation for the uncertainty in position in that problem is correct. in that case you're finding a more specific area than just the diameter.