Units for Uncertainty in Position


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Pranav Kadiyala 2A
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Joined: Wed Sep 30, 2020 9:58 pm

Units for Uncertainty in Position

Postby Pranav Kadiyala 2A » Mon Oct 26, 2020 1:04 pm

In a lot of the problems, the diameter of a certain atom is given to represent the uncertainty in position of an electron. How come uncertainty is measured in meters? Shouldn't the uncertainty be a volume (m^3)? Eg; not knowing where the electron is in the circular volume of an atom?

YZaarour_1E
Posts: 42
Joined: Wed Sep 30, 2020 9:51 pm

Re: Units for Uncertainty in Position

Postby YZaarour_1E » Mon Oct 26, 2020 1:11 pm

The uncertainty in position is a one-dimensional value, so you can assume that the atom is a flat shape and the uncertainty extends from left to right. A distance is a one-dimensional measurement, so the exponent is 1.

Samantha Pedersen 2D
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Re: Units for Uncertainty in Position

Postby Samantha Pedersen 2D » Mon Oct 26, 2020 3:54 pm

The uncertainty in position uses the same units as the units for position itself. The position of the electron is measured in meters, so the uncertainty in position is measured in meters too. I hope this helps!

Frankie Mele 2E
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Joined: Wed Sep 30, 2020 10:09 pm

Re: Units for Uncertainty in Position

Postby Frankie Mele 2E » Tue Oct 27, 2020 1:34 pm

The units also have to be in meters because when using uncertainty of position to solve for delta velocity, your final answer has to be in (m/s).

Mackenzie Van Valkenburgh 3G
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Joined: Wed Sep 30, 2020 9:36 pm

Re: Units for Uncertainty in Position

Postby Mackenzie Van Valkenburgh 3G » Fri Oct 30, 2020 6:41 pm

Mathematically, the units of uncertainty in position must be meters in order for the other units in the Heisenberg equation to cancel out correctly while you are solving for a value. Conceptually, the reason that m is to the first power and is not m^3 is because we assume that the electron's possible position is one-dimensional, and therefore measured like a linear distance. Some questions actually state that you should model the electron as being inside of a flat square rather than a 3-D box, which can help you visualize the uncertainty in position in 1 dimension rather than within a volume. I hope this helps!

Aayushi Jani 2D
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Joined: Wed Sep 30, 2020 9:51 pm

Re: Units for Uncertainty in Position

Postby Aayushi Jani 2D » Fri Oct 30, 2020 8:56 pm

The uncertainty in position refers to the position of the electron (which is in meters), so it would also be in meters.

Stacey Phan 3I
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Re: Units for Uncertainty in Position

Postby Stacey Phan 3I » Fri Oct 30, 2020 9:12 pm

Use meters so the units cancel out correctly!


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