The shortest time
that a point takes to return to the initial position
(one vibration) is called period,
T. In this example, every vibration is marked with a
short pause.
The number of vibrations per second
is called frequency and
is measured in hertz (Hz). Here's the equation for
frequency:
f = 1 / T
The shortest distance between peaks,
the highest points, and troughs, the lowest points,
is the wavelength, .
By knowing the frequency of a wave
and its wavelength, we can find its velocity. Here is
the equation for the velocity
of a wave:
However, the velocity of a wave is
only affected by the properties of the medium. It is
not possible to increase the speed of a wave by
increasing its wavelength. By doing this, the number
of vibrations per second decreases and therefore the
velocity remains the same.
The amplitude
of a wave is the distance from a crest to where the
wave is at equilibrium. The amplitude is used to
measure the energy transferred by the wave. The
bigger the distance, the greater the energy
transferred.
Example:
A radio wave has a
frequency of 93.9 MHz (93.9 * 10^{6} Hz).
What is its period?
f =
93.9 * 10^{6}
Hz
f = 1 / T
T = 1 / f
T = 1 / 93.9 x 10^{6}
Hz
T = 1.06 x 10^{8}
s
