Amplitude – the amplitude (A) of a wave is the maximum displacement of a particle from its equilibrium position.
Wavelength – the wavelength (λ) of a wave is the minimum distance in which the wave repeats itself.
For a transverse wave, it is the distance between two successive crests or two successive troughs.
For a longitudinal wave, it is the distance between successive compressions or successive rarefactions.
Generally, it is the distance between any two successive points on adjacent waves.
All the particles within a medium, through which a wave propagates, vibrate or oscillate.
Period – the period (T) of a wave is the time taken by a particle to complete one oscillation.
It is the time taken to produce one complete wave.
S.I. unit: second (s).
Frequency – the frequency (f) of a wave is the number of oscillations completed by a particle per unit time.
It is the number of complete waves produced in one second.
It is numerically equal to the reciprocal of the period of the wave.
f = 1/T
S.I. unit: s-1 (Hz)
Speed – the speed (v) of a wave is the distance travelled per unit time.
Since the wave travels a distance of one wavelength (1λ) in one period (1T), the wave speed is given by: v = λ/T è v = f λ
(f = 1/T)
Phase shift – the phase shift (Φ) of a wave gives the current position of the wave relative to the reference position (i.e. the origin).
It is usually expressed in terms of degrees or wavelengths, where 360° corresponds to one wavelength (1λ). 360° à 1λ
180° = λ/2
90° = λ/4
If at times t1 and t2 the position of a particular wave along the horizontal axis is given by the graphs below:
(i) [insert PICTURE 4-6]
(ii) [insert PICTURE 4-7]
At time t2, the position of the wave has shifted by a half of a wave, i.e. by a half of a wavelength. Therefore, Phase difference = λ/2 = 180°