T1.1 Wave Motion (Some Important terms)


Hmmm ..... So Motion can be described as fast but not frequent. Now we can see why language is important. Give attention to the meaning of words.


Here are some important terms which are used to describe  the wave motion.
Wave Length ($\lambda$): The distance between any two nearest particles of the medium vibrating in same phase, which is equal to one wavelength. The distance between two nearest crests (or troughs) is equal to one wavelength $\lambda$m measured in meter ($m$), as shown in figure below.
The distance traveled by the wave during the time at which any particle of the medium completes one vibration about its mean position is called the wavelength ( Ref. Principle of PHYSICS - XII).

Crest: The particle move upward i.e. maximum distance above from the mean position is called Crest.
Trough: The particle move downward i.e maximum distance below from the mean position is called Trough.


Frequency ($f$ or $\nu$): The number of oscillations completed by the particles of the medium in one second, or a cycle is repeated within a specific length of time.  It is measured in Hertz ($Hz$).
Mathematically:
$f = \frac{1}{T}$
Amplitude ($a$): The maximum displacement of a medium from a mean point (or equilibrium), as shown in figure above. It is measured in meter (m).
Phase: The state of motion of a particle (i.e where is the particle and what its direction of motion is) at a given place  and time is called phase, or a part of a repeated uniform pattern of occurrence of a phenomena. It is measured in terms of angle called Phase angle.
Phase angle ($\phi$): The angle between two similarly varying quantities. It s denoted by $\phi$. Mathematically:
$\phi = \frac{2\pi}{\lambda }x$ ; Where $x$ is a displacement and $\lambda$ is a wave length.
Period ($T$): The time required for one complete cycle for a vibrating (moving) particles. The time interval which the motion of an vibrating (moving) particle begins to repeat itself. Mathematically:
$T = \frac{1}{f}$
Wave velocity ($V$): The distance traveled by a wave in one second is called wave velocity. 

or, $V$ = $\frac{\lambda}{T}$

or, $V$ = $\lambda f$
So, the wave moves through one wave length in one period of oscillation.
Wave speed: $C = f\lambda$; where $C$ is Velocity of Light, $F$ is frequency, $\lambda$ is wave length.
Path Difference: If we measured the distance traveled by waves, then compare those difference distance between two waves is called the path difference. It is measure in meter (m).
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