How High Must Charged Particles Be for Radio Wave Interference?

[patriots1049]

Homework Statement

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?

Homework Equations

lamba = v/f

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?

 

[davidelete]

Homework Statement

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 recerved 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?

Homework Equations

lamba = v/f

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?

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...

 

[patriots1049]

Can someone assist me in solving this problem?

 

[davidelete]

I wish I could.