How Long Is the Wave Packet from a Radar Transmitter?

[lockedup]

Homework Statement

A 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?

Homework Equations

ΔkΔx≈1
ΔωΔt≈1

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.

 

[marcusl]

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?

 

[lockedup]

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?

a) v = .02 m/.00000025 s = 80000 m/s What do I do now?

b) Ooh... *facepalm* f = c/λ = 3e8/.02 = 1.5e10

 

[marcusl]

b is correct, a not at all. What is the speed of light?

 

[lockedup]

3e8(.25e-6) = 75

*facepalm again* Thank you