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!

Simple wave packets problem

  1. Mar 17, 2012 #1
    1. The problem statement, all variables and given/known dataA radar transmitter used to measure the speed of pitched baseballs emits pulses of 2.0 cm wavelength that are .25 μs in duration. a) What is the length of the wave packet produced? b) To what frequency should the receiver be tuned? c) What must be the minimum bandwidth of the receiver?



    2. Relevant equations
    ΔkΔx≈1
    ΔωΔt≈1



    3. The attempt at a solution
    Part c) was easy enough. ΔωΔt≈1 → Δω≈1/Δt = 1/.00000025 = 4000000

    4000000/2π = 6.36e5 Hz

    The others? I have no idea. The section of the text barely defines what a wave packet is and I've read through it at least three times.

    I would appreciate some help getting started.
     
  2. jcsd
  3. Mar 17, 2012 #2

    marcusl

    User Avatar
    Science Advisor
    Gold Member

    a) What is the propagation speed of radio waves? What physical length does a 0.25 us pulse correspond to?
    b) You know the wavelength, what frequency does that correspond to?
     
  4. Mar 17, 2012 #3
    a) v = .02 m/.00000025 s = 80000 m/s What do I do now?

    b) Ooh... *facepalm* f = c/λ = 3e8/.02 = 1.5e10
     
  5. Mar 17, 2012 #4

    marcusl

    User Avatar
    Science Advisor
    Gold Member

    b is correct, a not at all. What is the speed of light?
     
  6. Mar 17, 2012 #5
    3e8(.25e-6) = 75

    *facepalm again* Thank you
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Simple wave packets problem
  1. Simple wave problem (Replies: 2)

  2. Wave Packets (Replies: 0)

Loading...