Wave is a transfer of energy, in the form of disturbance through
some medium, without translocation of the medium. A wave having a short
duration is called pulse. Waves that vibrate in repeating cycles
illustrate periodic motion or harmonic motion. One
complete oscillation is called cycle.
Transverse vibration occurs when vibration of the medium is
perpendicular to the direction of energy transfer. The maximum and
minimum positions on a transverse wave are called the crest and trough.
Longitudinal vibration occurs when the medium vibrates parallel to the
direction of energy transfer. Longitudinal vibrations consist of
regions of compression and rarefaction.
Frequency (f) describes the number of cycles
occurring in a given unit of time. The SI unit for frequency is
hertz (Hz). The units cycles / second are also used.
Frequency = Number of cycles / Time Interval
Period (T) is the time required to complete
one full cycle. Period and frequency exhibit a reciprocal relationship.
The amplitude of a wave is the maximum displacement from the
equilibrium or the rest position.
Wavelength (l) is the distance between
successive crests or successive troughs. The wavelength is the shortest
distance between two points in phase (or two points that have identical
characteristics). The universal wave equation
(v = fl) is said
to be universal because it applies to all types of waves. The universal
wave equation can be used to solve various problems relating to wave
Reflection of Waves. When a series of waves strikes an obstacle,
the waves are reflected. Waves falling upon the barrier are called
incident waves and waves reflecting from the barrier are called
reflected waves. Reflection of waves can be summarized in the following
law of reflection: the angle of incidence
equal to angle of reflection (qr).
Here is a diagram illustrating the reflection of waves:
Refraction of Waves. Refraction occurs at the boundary between
two different media and causes the waves to change direction as shown
in the following diagram:
Diffraction of Waves. Diffraction is the bending that occurs
when a wave passes around the edge of an obstacle. Waves having longer
wavelengths are diffracted more than those with shorter wavelengths.
When waves pass through a slit, diffraction is maximized when the
wavelength and the slit width are within the same order of magnitude.