Question

A radio wave has a wavelength of 300 m. The wave moves with a speed of 3.0 × 108 m/s. What is the frequency of the radio wave? A. 1.0 × 106 Hz B. 1.0 × 10-5 Hz C. 1.0 × 10-6 Hz D. 1.0 × 105 Hz

Answer 1

           Frequency  =  (speed)  /  (wavelength)

                             = (3 x 10⁸ m/s)  /  (300 m)

                             =      1 x 10⁶ per sec

                             =      1 mHz 

This frequency is the " 1000 " or " 100 " that's marked
in the middle of your AM radio dial.

If there's an AM station in your city that broadcasts on 1000 kHz
and you tune your radio to it, you're picking up radio waves 
that are 300 meters long.  (about 0.19 of a mile)