Wave  (def.)    A wave is a transfer of energy in the form of a disturbance, usually through a material, or medium.

Vibration All waves are caused by a vibration of some kind.  Vibrations (and waves) have terms associated with them which help to describe them:

Period T:  time for one complete vibration

Frequency f:  number of vibrations in a given amount of time (measured in hertz Hz)

Period and time are related by the following:

                T =  1 /f   (1 Hz = 1 cycle/s)

Example: A pendulum in a clock makes 240 complete cycles in 60s.  What is the frequency and period of the pendulum?

                Period = time required

                                # of cycles

                T = 60 s/240 = 0.25 s

                f = 1/T

                f = 1/0.25

                f = 4.0 hz

Wave Motion:

The medium (or material) in which a wave travels does not move from one place to another.  However the wave does move.  Waves move at different speeds depending on the type of wave and the medium in which it travels.  Ex:  Light travels at 3 x 10⁸ m/s having wavelengths on the order of 10-9m whereas sound travels at 332 m/s and has a wavelength on the order of a metre.

Wave Properties:

There are 4 properties normally associated with a wave:

Amplitude:  maximum height of the wave crest

Wavelength (l):  the distance between two identical points on a wave

Frequency (f):  number of waves passing a point in a given time (remember: f = 1/T)

Velocity (v):  the speed at which the wave travels:

                v = fl     or    v =     l/T

Check out this site on Waves

Assignment:  Wave Characteristics