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Uncertainty Principle Question

  1. Feb 11, 2014 #1
    1. The problem statement, all variables and given/known data

    Laser can now be designed to emit pulses of light smaller than 30 microns wide
    in their direction of motion.

    (a) Estimate the uncertainty in the momentum of a
    photon in such a pulse.

    (b) The momentum of a photon is p=h/λ. Estimate the
    uncertainty in the wavelength of a photon in the pulse, assuming a nominal
    wavelength of 800 nm.


    2. Relevant equations

    ΔxΔp ≥ h/4π, p = h/λ

    h being Planck's constant of 6.626 * 10-34 J*s

    3. The attempt at a solution

    My confusion with this problem stems from the fact that I'm not sure if Δx = 30*10-6m

    If that is the case, then I did Δp ≥ h/4π*Δx.

    Part a: Δp ≥ 1.757 * 10-30 kg*m/s

    For part b, I then took the Δp value of 1.757 * 10-30 kg*m/s and plugged it into p = h/λ. I then got λ = 0.000377 m.

    Is this the right method?
     
  2. jcsd
  3. Feb 11, 2014 #2
    Seems good.
     
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