1. The problem statement, all variables and given/known data Typical AM radio waves usually have a frequency between 540 kHz and 1400 kHz. FM radio waves tend to have frequencies between 89 MHz and 105 MHz. Both types of waves travel at the speed of light. In terms of diffraction, use this information to help explain why in many low lying valleys in mountainous regions, AM reception is much clearer than FM reception. 2. Relevant equations nil. 3. The attempt at a solution Well, I'm not so sure. I know that the FM waves obviously have a higher frequency so I am guessing that the answer lies somewhere there. Could someone give me the jump-start that I need to get going on this question? Thanks a lot!