Textbook sometimes complicate wave
concepts unnecessarily. Here is one
example; confusing words are shown
in capital letters.
Quick Quiz 13.2
"Sound waves (v=340 m/s) from a musical
performance are ENCODED onto radio
waves for transmission from the radio
studio to your home receiver. A radio
wave traveling at c=3*10^8 m/s with the
wavelength of 3 m CARRIES a sound
wave that has a wavelength of 3 m in air.
which has the higher frequency, the radio
wave or the sound wave?"
We know that the word ENCODED refers
to either AM or FM. But a student may be
confused. S/he can also be confused by
the idea of "one wave carrying another,"
although we know that is correct.
In the context of the first physics course
this problem can be presented in better
ways. For example, something like this:
"Two waves (radio and sound) have the same
wavelength (3 m) but their velocities are 3*10^8
and 340 m/s, respectively. What can we say
about the frequencies of these two waves?"
Yes, I know that this is slightly off the topic. But
it is about waves. Many of us are teaching
waves at this time of the year.
Ludwik Kowalski