Question

Your firm has been hired to design a system that allows airplane pilots to make instrument landings in rain or fog. You've decided to place two radio transmitters 52m apart on either side of the runway. These two transmitters will broadcast the same frequency, but out of phase with each other. This will cause a nodal line to extend straight off the end of the runway. As long as the airplane's receiver is silent, the pilot knows she's directly in line with the runway. If she drifts to one side or the other, the radio will pick up a signal and sound a warning beep. To have sufficient accuracy, the first intensity maxima need to be 66m on either side of the nodal line at a distance of 3.0km .What frequency should you specify for the transmitters?

Answer 1

i have done a similar question with just 2 changes they are (i have used 50 in place of 52 and 60 in place of 66 and remaining all is same just substitute it any qsns ping me ASAP )

Signal emitted from point A: sin(2?f(t - sqrt((y-50)^2 + x^2))/c)
Signal emitted from point B: - sin(2?f(t - sqrt((y+50)^2 + x^2))/c)

For y = 0, these two signals will be equal in magnitude and opposite in sign: they will cancel.

In order to achieve the first antinodes, the difference in path must introduce an additional phase difference of ?:
2?f(t - sqrt((y-50)^2 + x^2))/c = (2?f(t - sqrt((y+50)^2 + x^2))/c