[填空题]
(a) AM radio signals have fre,;y iy9g9-j k dmhrx-oquencies between 550 kHz and 9t 1k21ecpfjof 7mvw/1600 kHz (kilohertz) and travew7mk fv p foj/ec129t1l with a speed of $ 3\times10^{8 }$ m/s What are the wavelengths of these signals? m to m(b) On FM, the frequencies range from 88.0 MHz to 108 MHz (megahertz) and travel at the same speed; what are their wavelengths? m to m