# Homework Help: Diffraction and Interference

1. Feb 9, 2009

### patriots1049

1. The problem statement, all variables and given/known data
An aircraft causes a horizontal layer of charged particles to be formed in the atmosphere. Radio waves are relected without phase from this layer. Radio waves of frequency 8.00 x 10^2 kHz are received at a location 12 km from the transmitter. What is the minimum height of the layer of particles if radio reception fades due to destructive interference between the direct beam and the reflected beam?

2. Relevant equations

lamba = v/f

3. The attempt at a solution

I have found a wavelength of 375 m. Now i'm not sure what to do from here. The answer is supposed to be between 1 and 2. Can someone help me get past this road block?

Last edited: Feb 9, 2009
2. Feb 9, 2009

### davidelete

Ah yes, quite a familiar problem. The workings should not be too hard. I believe that the equation is x/L=lambda/d, if I'm not mistaken, unless that is a predefined equation designated by your instructor specifically for this problem...

3. Feb 9, 2009

### patriots1049

Can someone assist me in solving this problem?

4. Feb 10, 2009

### davidelete

I wish I could.