Question

4. An AM radio antenna has 3000 loops with diameter 0.20 m; a radio station makes its 2 nt magnetic field oscillate at 1400 kHz pointing left, then right. a) which coil orientation is best for the antenna's reception? { ABC} A b) calculate the voltage from the antenna ela

Answer 1

loops Ans.) number of ne: 3000 Diameter of the loop = d = o.am frequency of oscillation = f =1400kitz f: 1400 x103 HZ magnetic field B=anT=2x109 T

. ca) The changing magnetic field creates a changing magnetic flux through the loop. This changing flux induces an emf in the loop For better reception we want this emf to be largest which will happen When the flux change is maximum flux through the lcrop at a time is maximum Now since the magnetic field Oscillates from left to right, so there will be negligible flux associated with orientations A anda. Maximum flux will be associated with orientation B 0 C

A and C. Planes of loops A and a contain the magnetic field and hence and hence no fry the ou ди Plane of B is perpendicular to the magnetic field and hence the flux in maximum through B. so orientation B is best. b) voltage from the antenna - = hate of change of magnetic feux throgn the loop -UB AF A area of the loop = 3000X2X10%&*14c0X, 18 = 2 XQ XA X(0.23²x14x10' 4 0-263894 v V