1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: 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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted