Wave Motion and its Variables

The wavelength is the minimum distance between any two identical points on adjacent waves.

period is the time required for two identical points (such as the crests) of adjacent waves to pass by a point.

The frequency of a periodic wave is the number of crests (or troughs, or any other point on the wave) that pass a given point in a unit time interval. The maximum displacement of a particle of the medium is called the amplitude A of the wave.

Waves travel with a specific speed, and this speed depends on the properties of the medium being disturbed.

A traveling wave that causes the particles of the disturbed medium to move perpendicular to the wave motion is called a transverse wave.

Example

Let us consider to flick one end of a long rope that is under tension and has its opposite end fixed, as shown in figure below. A single wave bump is formed and travels along the rope with a definite speed. This type of disturbance is called a traveling wave, and figure represents four consecutive “snapshots” of the creation and propagation of the traveling wave. The rope is the medium through which the wave travels.

A single pulse, in contrast to a train of pulses, has no frequency, no period, and no wavelength. However, the pulse does have definite amplitude and definite speed. The properties of particular medium that determine the speed of the wave are the tension in the rope and its mass per unit length. The shape of the wave pulse changes very little as it travels along the rope.

A traveling wave that causes the particles of the medium to move parallel to the direction of wave motion is called a longitudinal wave.

Example

The left end of the spring is pushed briefly to the right and then pulled briefly to the left. This movement creates a sudden compression of a region of the coils. The compressed region travels along the spring .The compressed region is followed by a region where the coils are extended. The direction of the displacement of the coils is parallel to the direction of propagation of the compressed region.

Sound waves are another example of longitudinal waves. The disturbance in a sound wave is a series of high-pressure and low-pressure regions that travel through air or any other material medium.

Waves and Propagation

Resonance
Wave Propagation
Transverse and Longitudinal Waves

Simple Harmonic Motion Displacement ,Velocity and Acceleration 

Time Period,Frequency and Phase of a body in SHM 

Problems on SHM displacement,velocity and Acceleration 

Energies of Body in Simple Harmonic Motion 

Physics Mechanics transverse longitudinal waves

As per physics definition a wave is a periodic disturbance which propagates energy from place to other. One of the important type of wave is mechanical wave and it need materiel medium for propagation.

Mechanical waves are further classified depending on the space up to where they propagate.If the wave propagate for infinite distance and never come back then it is called progressive wave.If the wave is confined between any two finite points then it is called stationary wave.

A progressive wave is further classified into two types basing on the vibration of particles and direction of motion of wave.

If the direction of vibration of particles of elastic medium is parallel to direction of wave propagation it is called longitudinal wave and if the vibration of particles is perpendicular to direction of wave motion then the wave is called transverse wave.

The following is the representation of longitudinal progressive wave and we can notice the compressions and rarefactions . A compression is a place where particles are crushed close and rarefaction is a place where particles are bit separated.

The compressions and rarefactions are systematic and they are separated by fixed distance.Two successive compressions and rarefactions are constantly separated by a fixed distance and it is called wave length.


Further we can draw a case of transverse wave as shown below.

In transverse waves, the particle motion is normal to the direction of propagation of the wave. Therefore, as the wave propagates, each element of the medium undergoes a shearing strain. Transverse waves can, therefore, be propagated only in those media which can sustain shearing stress, such as solids and strings, and not in fluids.

Fluids as well as solids can sustain compressive strain; therefore, longitudinal waves can propagate in all elastic media. For example, in medium like a steel bar, both transverse and longitudinal waves can propagate while air can sustain only longitudinal waves.

Related post

How does waves propagate ?

Simple Harmonic Motion Displacement ,Velocity and Acceleration 

Time Period,Frequency and Phase of a body in SHM 

Problems on SHM displacement,velocity and Acceleration 

Energies of Body in Simple Harmonic Motion 

Time Period of Simple pendulum 

Problems on Simple Pendulum with Solutions 

Loaded spring in simple harmonic motion 

Damped Oscillations and Forced Oscillations

Waves in Physics Introduction

A wave is a periodic disturbance. Wave in physics carries different kinds of energies from one place to other. Broadly waves are of two types by the name mechanical and non mechanical waves.Mechanical waves needs a medium for prorogation and non mechanical waves don't need any medium for prorogation. They can travel through vaccum.

For mechanical wave propagation the medium shall have elastic nature and shall contain inertial property.In the case of wave propagation no particle of medium displaces permanently from their mean position and they just vibrate about their mean position.During that process they transfer energy to their next particles and this process continues until the destination is reached.

These patterns of transfer of energy which move without the actual physical transfer or flow of matter as a whole, are called waves.In a wave, information and energy, in the form of signals, propagate from one point to another but no material object makes the journey.

The other kind of waves are matter waves.Matter waves are associated with moving electrons, protons, neutrons and other fundamental particles, and even atoms and molecules.

Wave propagation of sound waves in air is done in the following way: As the wave passes through air, it compresses or expands a small region of air. This causes a change in the density of that region, δρ, this change induces a change in pressure, δp, in that region. Pressure is force per unit area, so there is a restoring force proportional to the disturbance. If a region is compressed, the molecules in that region are packed together, and they tend to move out to the adjoining region, thereby increasing the density or creating compression in the adjoining region.

Consequently, the air in the first region undergoes rarefaction. If a region is comparatively rarefied the surrounding air will rush in making the rarefaction move to the adjoining region. Thus, the compression or rarefaction moves from one region to another, making the propagation of a disturbance possible in air.

SHM related topics

Resonance
Damped simple harmonic motion
Simple Pendulum
What is periodic and Oscillatory Motion is ? Displacement in Oscillatory motion
Simple Harmonic Motion
Velocity and acceleration of SHM
Energy of particle in SHM