Longitudinal Wave
Hey students in this article we are going to deal with one of the important type of wave i.e. longitudinal wave. We know that wave is a small disturbance travelling in medium. When disturbances are travelled through medium it carries energy throughout the medium. Here in this article we are dealing with one among the widely applied mode of energy transfer by means of longitudinal wave.
Imagine that your teacher has punished you for incomplete homework. For this he asked 12 students who were punished to stand in a queue keeping small distance between them and facing towards wall. Now suddenly teacher pushed a last student when he wasn’t aware of this, so he will fall on next one. i.e. 12th will fall on 11th student, due to sudden disturbance 11th will also fall on 10th one and so on 2nd will fall on 1st and 1st will collide on the wall. Isn’t it interesting mode of punishment? What did you observed here? Here students are pushed towards the direction of wall, and their movement also takes place towards the same direction. This is nothing but the visualization of energy transfer due to longitudinal wave.
Longitudinal wave is defined as ‘the wave in which the particles of medium vibrate in a direction parallel to direction of propagation’. Eg. Sound wave produced with the help of tuning fork.
Since the direction of propagation of wave and direction of vibration of particles is parallel, medium divides itself in to alternate compressions and rarefactions as shown in fig. below.
Compression: Compressions are the reasons where particles are crowded. During formation of compression the volume of medium decreases so as to increase the density of medium. Pressure at compression also rises due to rise in density.
Rarefaction: Rarefactions are the reasons where the particles are widely spaced. During formation of compression, volume of medium decreases so as to increase the density. This decreases the pressure of particles of medium.
One compression and one rarefaction form a set of longitudinal wave. The distance between two successive compressions / rarefaction or distance between centres of two consecutive compression / rarefaction is known as wavelength of longitudinal wave.
Time required to complete one set of longitudinal wave is known as period of longitudinal wave.
Longitudinal wave transfers energy in the medium.
Longitudinal waves can travel through solid, liquid as well as gases.