Two antennas located at points A and B are broadcasting radio waves of frequency
ID: 2168610 • Letter: T
Question
Two antennas located at points A and B are broadcasting radio waves of frequency 95.0 MHz, perfectly in phase with each other. The two antennas are separated by a distance d= 9.30 m. An observer, P, is located on the x axis, a distance x= 58.0 m from antenna A, so that APB forms a right triangle with PB as hypotenuse.
a.) What is the phase difference between the waves arriving at P from antennas A and B? Answer: 1.474 radians
b.) Now observer P walks along the x axis toward antenna A. What is P's distance from A when he first observes fully destructive interference between the two waves?
c.) If observer P continues walking until he reaches antenna A, at how many places along the x axis (including the place you found in the previous problem) will he detect minima in the radio signal, due to destructive interference?
Explanation / Answer
L = (2n + 1)*/2. ........(1)
Find the wavelength.
The first destructive interference will occur when L = /2.
Now L = sqrt(9.3^2 +x^2) - x...(2)
Put L = /2 and solve for x.
Repeat the procedure for L = 3/2, 5 /2......until x becomes negative.