Describe what is meant by frequency modulation.
A sinusoidal carrier wave has frequency 
and amplitude 
. It is to be frequency modulated by a sinusoidal wave of frequency 
and amplitude 
. The frequency deviation of the carrier wave is 
. Describe, for the carrier wave, the variation (if any) of
the amplitude,
the frequency.
State two reasons why the cost of FM broadcasting to a particular area is greater than that of AM broadcasting.
and a lower limit of 
at 
.
