Wave Motion



Clear your concept in Physics, book a Physics Tutor with us today!

             Mechanical waves are the waves which require an elastic medium to travel. The examples of this type of waves are sound waves, water waves and waves traveling through guitar. The mechanical waves originate from a source that create disturbance in the medium and the wave travels through the medium due to its elastic nature. However, in the microscopic level, the forces between the atoms are responsible for the propagation of mechanical waves.

The waves can be classified in following manner:

1- On the basis of direction: - When the direction of motion of the particles is perpendicular to the direction of propagation of the wave, the wave is called transverse wave. The examples of such waves are: water waves, waves created due to the vibration of a string. When the direction of motion of the particles is along the direction of motion of the wave, the wave is called longitudinal wave. The examples of such waves are: sound waves in a gas, the waves traveling through a spring.

2- On the basis of periodicity: When the particles in a wave move with respect to time then the wave is called a periodic or harmonic wave. The example of such wave is the periodic train of waves along a string.

3- On the basis of the shape of wave fronts: The shape of wave fronts can be circular and planar in two dimensions where as in three dimensions it can be spherical. In addition, there can be many more shapes of wave fronts. Accordingly there waves can e of different types.

For the waves traveling along positive x direction the transverse displacement is given as: y(x, t) = f(x - vt) and for the waves traveling along negative x direction the transverse displacement is given as: y(x, t) = f(x + vt). This concept is applicable for both longitudinal and transverse waves.

The wave length (λ), velocity (v) and time period (T) of a wave are connected to each other as: λ= vT. And the inverse of time period is called the frequency of the wave:

                                         f= 1/T

The wave number (k) is given by, k = 2π/λ. And the angular frequency (ω) is defined by,

                                       ω = 2 π f

Now the velocity of the wave is given by,

                                  V = λf = λ/T = ω/k