Uncertainty of Position of Electron 1/100xspeed of light


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Jolie Sukonik 2B
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Joined: Wed Sep 30, 2020 9:44 pm

Uncertainty of Position of Electron 1/100xspeed of light

Postby Jolie Sukonik 2B » Mon Oct 26, 2020 9:15 pm

Calculate the uncertainty (indeterminacy) in position of an electron if its uncertainty in speed is one hundredth the speed of light.

For this I first found delta v: 0.01(3.0 x 10^8m/s) = 3.0 x 10^6 m/s
Then I found delta p: (9.1 x 10^-31kg)(3.0 x 10^6 m/s)
Then I found delta x: (h)/(4pi)(2.7 x 10^-24)
but the answer I got was none of the answer choices below. Can someone tell me where I went wrong?

A. Delta x >= 2 x 10-11 m

B. Delta x = 11 m

C. Delta x >= 2 x 10-15 m

D. Delta x = 15 m

Selena Quispe 2G
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Joined: Wed Sep 30, 2020 10:01 pm
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Re: Uncertainty of Position of Electron 1/100xspeed of light

Postby Selena Quispe 2G » Mon Oct 26, 2020 9:24 pm

Hi! Your work is correct maybe you just messed up when calculating. I like to make sure Planck's constant is always in parenthesis so maybe try that (6.626*10^-34)/4pi=(5.2728*10^-53)/(2.73*10^-24)=2.0*10^-11m. I hope this helps!
Last edited by Selena Quispe 2G on Mon Oct 26, 2020 9:24 pm, edited 1 time in total.

Tessa House 2A
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Joined: Wed Sep 30, 2020 9:52 pm
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Re: Uncertainty of Position of Electron 1/100xspeed of light

Postby Tessa House 2A » Mon Oct 26, 2020 9:24 pm

Hi,
Your steps look correct and when I plugged in those values into my calculator, I got the first answer choice if you round to one significant figure. Are you sure you calculated it correctly? To be sure, make sure you divided h by both of the values in the denominator by putting parenthesis around them. Otherwise, your work looks correct because you should solve for delta p and then delta x!


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