The relationship between spatial and temporal periods and frequencies is extremely important to be comfortable with and to build intuition about. We go through a few examples towards this end.
We return to our taut string or cord (or spring as here)
which we have strung out so
the wave-velocity which it supports is
Thus if I produce a harmonic wave with frequency
f=2Hz I expect a wave-length
which is in agreement with observations
Sound velocity in air is 330 m/s so a sound
with a frequency of 330Hz (such as that of a typical voice)
has a wavelength
If we consider
radio-waves say from WJHU 88.1MHz the velocity relevant is
the velocity of electromagnetic radiation in vacuum (more or less)
so we get
Not a very different wave length from sound because the speed of light is so
much greater than the speed of sound.
For visible light then we tend to know the wave length so lets
calculate the frequency of those oscillations of the electric and
magnetic fields.
