A radio transmitting station operating at a frequency of 120 MHz has two identical antennas that radiate in phase. Antenna B is 9 m to the right of antenna A. consider point P at a horizontal distance x to the right of antenna A as shown in figure. The value of x and order for which the constructive interference will occur at point P are

Answer

B, C, D

Explanation

`:. lambda = c/f = (3xx 10^8)/(120 xx 10^6) = 2.5m`
` (##DCP_V05_C32_E01_035_S01.png" width="80%">
` Deltax = (BP-AP) = (9-2x) = nlambda`
`:. x=(9-nlambda)/2 = (9-2.5n)/2`
Now, substituting n= 1,2,………… etc.
We can find different values of x.
`x_1 = 3.25m` for `n=1`
`x_2 = 2.0m` for `n=2`
and ` x_3 = 0.75m` for `n=3 `
Similarly, we will get three points at same distance from other point B.