The speed of radio waves is equal to electromagnetic wave speed i.e.3108m/s Given, the distance of radio station, s=200km =200×103m Time taken by radio wave to his toner t=
s
c
=
200×103
3×108
=666×10−6 =666µs The wave emitted send out per second =972kHz =972×103Hz =9.72×105 crest per second