Question

The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station approaches you for license what broadcast frequency will you allot ?
(A) 2750 kHz (B) 2900 kHz
(C) 2250 kHz (D) 2000 kHz

Answer 1

we will allot 2000kHz broadcast frequency to another AM station.

AM wave frquency contains 3 frequencies,

$f_{c} ,f_{c}+f_{m},f_{c}-f_{m}$

here,

$f_{c}=\frac{250}{0.1}=2500kHz\\ f_{m}=250kHz$

hence, range of signal of the given radio station is 2250kHz to 2750 kHz.

so ,we will allot another AM station broadcast frequency which will not overlap with this range.

so only option 2000kHz can be choosen as broadcast frequency for another AM station as range for that will be 1800-2200 kHz.

Therefore,we will allot 2000kHz broadcast frequency to another AM station.