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Homework Help: Estimate the uncertainty in electron's position.

  1. Apr 22, 2016 #1
    1. Question
    The speed of an electron is known to be between 6.0×10^6 m/s and 6.7×10^6 m/s . Estimate the uncertainty in its position.

    2. Relevant equations

    ΔpΔx ≥ h/2π
    (mΔv) Δx ≥ h/2π (Since Δp= mΔv)

    Δx≥ h/2π(mΔv)

    h= 6.63*10-34 J*s
    c= 3.0*108
    mass of electron= 9.11*10-31

    3. The attempt at a solution
    (6.63*10^-34)/(2pi(9.11*10^-31)*(6.7*10^6 - (6*10^6))
    = 0.00000000016546 m

    Apparently this is incorrect. What am I doing wrong?

    Attached Files:

  2. jcsd
  3. Apr 22, 2016 #2


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    The range of velocities in that picture is different from the one in your problem.
  4. Apr 22, 2016 #3
    I am aware, that is why I wrote my work in the 3rd step of the post. I used my own velocity range.
  5. Apr 22, 2016 #4


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    Why is it not correct? Using your own velocities, I also got the same value. Do I miss something about what you actually want to figure out?
  6. Apr 22, 2016 #5
    I'm not sure. My answer was marked incorrect which is strange. I understand the problem and how to do it. I figured maybe my work was wrong or a small error?
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