The relation between these quantities is given by f = 1 / T. From this example, it is obvious that the period of a wave completely defines its frequency and vice versa. As an example, a wave with a period T = 0.25 s takes ¼ of a second to complete a full vibration cycle (crest – trough – crest) at a certain location and thus performs four vibrations per second. The unit of frequency is Hertz (Hz) and 1 Hz is the reciprocal of 1 second. The frequency f of a wave is the number of vibration cycles per second at a certain location X. The period of a wave is given in seconds.
#COLORFUL WAVE GIVE FULL#
This definition is identical with the statement that the period is the time the vibration at X takes to complete a full cycle from crest to trough to crest. The period T of a wave is the time that elapses between the arrival of two consecutive crests (or troughs) at a certain location X. The wavelength λ is the distance between two adjacent crests (or troughs) and is given in meters. The amplitude is the maximum disturbance of the medium from its equilibrium. In the case of a wave in a horizontal string, this value is identical with half of the vertical distance between the wave’s crest and its trough. In order to describe the basic properties of a wave, the following quantities have been defined for all kinds of waves: For optical radiation, the respective index of refraction is given in parenthesis Tab. 1: Velocities of sound and light in air and in water. The velocity of this propagation is generally abbreviated with the letter c (unit: meters per second, m / s) and depends on the medium and nature of the wave (see Tab. 1 below). Yet, the result can still be described as a periodic change of a physical quantity (the strength of the electric and the magnetic field) propagating into space.
In the case of an electromagnetic wave, the mechanism of propagation involves mutual generation of periodically varying electric and magnetic fields and is far more difficult to understand than sound. 2: Formation and propagation of a compression wave in air, a phenomenon colloquially called sound For example in the case of sound, the alternating rarefaction and compression of air molecules at a certain location results in periodic changes in the local pressure, which in turn causes the movement of adjacent air molecules towards or away from this location.įig.
The propagation is caused by the fact that the vibration at a certain location influences the region next to this location. 1: Formation and propagation of a wave in a string Like all other waves (waves in a string, water waves, sound, earthquake waves …), light and electromagnetic radiation in general can be described as a vibration (more general: a periodical change of a certain physical quantity) that propagates into space.
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