Slide 1: WAVE MOTION Wave Motion : Wave Motion Form of disturbance which travels through a medium due to repeated periodic motion of the particles of the medium about its mean position.
Types of wave motion:
Longitudinal waves Slide 3: Basic Variables of Wave Motion
Terminology to describe waves Crest: “Highest point” of a wave
Wavelength l: Distance from one crest to the next crest.
Wavelength l: Distance between two identical points on a wave.
Period T: Time between the arrival of two adjacent waves.
Frequency f: 1/T, number of crest that pass a given point per unit time Example : Example If a string is fixed at one end is given a sudden jerk, a disturbance in the form of a pulse travels along the length of the string i.e. particles vibrate perpendicular to the direction of propagation. speed of transverse wave : speed of transverse wave Speed of transverse waves in solids is given by:- ?=v(n/p) where n is the modulus of rigidity and p is the density of the material of the solid.
Speed of transverse waves in a stretched spring is given by:- v=v(T/m) where T is the tension and m is the linear density of the string. Slide 6: Longitudinal waves:
The particles of the disturbed medium move parallel to the wave motion. A longitudinal wave along a stretched spring. The displacement of the coils is inthe direction of the wave motion. Each compressed region is followed by a stretched region. : A longitudinal wave along a stretched spring. The displacement of the coils is inthe direction of the wave motion. Each compressed region is followed by a stretched region. Speed of a longitudinal wave : Speed of a longitudinal wave Speed of longitudinal wave in a solid is:-
V=v(k+4/3n)/p where k, n and p are the values of bulk modulus, modulus of rigidity and density of the solid respectively.
In case the solid is a long rod, the speed is:
v=v(Y/p) where Y is the Young’s modulus of the material.