## Calm Chapter 7, section 1, number 8greenspun.com : LUSENET : UR General Chemistry : One Thread |

hi, does anyone know how to get the value of the wavelength after knowing that there is a 2.1% value of uncertainty in the velocity? I know we have to do smetihng with the Heisenberg Uncertainty Principle but i'm still confused as to how 2.1% plays a role in it. thanks

-- Anonymous, April 12, 2000

The book gives an example (example 12.5) on how to find the uncertainty in velocity. The only difference in this CALM problem is instead of solving for dV, you solve for dX. The main equation is:dX * dP = h/(4*pi) where pi = 3.14 and dP = m*dV

Multiply the velocity you got in part 1 by the % value of uncertainty in the velocity (in your case, it's 2.1% = .021) and calculate for dP (the undertainty of momentum). After you do that, use the equation dX * dP = h/(4*pi) to solve for dX. That should give you the answer you want. Basically the % value of uncertainty is only used to calculate your velocity.

-- Anonymous, April 12, 2000

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